Letters to the Editor: Dark Side

We received a tremendous amount of response to the article Tales from the Dark Side: Putting Car Tires on Motorcycles in the July 2012 issue. We printed a representative sample of letters in the September 2012 issue. Below are the rest.



I just got done reading Eric Trow’s piece on riders who use car tires on their bikes. Good article! Maybe on a rat bike, but on a Gold Wing? I thought I was cheap! I use nothing but Dunlop’s on my Ultra Classic. Anything less, well just be sure your affairs are in order.

Dana Johnson, Virginia Beach, Virginia



An eerie tale by Eric Trow appeared recently, “Tales from the Dark Side,” Rider, July, 2012, about a small group of nonconformists whose claim to fame seemed to be that they fitted car tires onto cruiser-type motorcycles, and about how unsafe that was—although no accident data was supplied to substantiate that claim.  This group composed of, at most, a few thousand bikers.

There is a wealth of information on this topic, which should be of considerable value to many readers. To begin, motorcycles began from the development of bicycles as far back as the end of the nineteenth century as small motors were hung somewhat haphazardly onto the frames of the safety bicycle, sometimes driving the front wheel, sometimes the rear, above the rear wheel, in the center of the frame, and so on. At the time, the bicycle tires were of primitive design and blowouts or the tire coming off the rim were quite common. Later, as speeds became faster, roadways improved, and motorcycles were developing, so the wheels became stronger and wider and tires from the small three- and four-wheel cycle cars were fitted to motorcycles. These tires were distinguished from the larger car and small truck tires only by being narrower, and often of larger diameter than “regular” car tires. And so it continued for many years.

It was only in the most recent history, perhaps from the post WWII era, that there was any real development of special tires for motorcycles, as distinct from car or truck tires. Now, speeds for cars and motorcycles were approaching or exceeding 100 mph and the need for specialized tire design for both was apparent. But even then, some motorcyclists were still fitting car tires onto motorcycle rims, so much so, that in the interests of safety, the International Tire & Rim Association, which governs the sizes and precise specifications of all tires and rims for all types of vehicles, including cars and motorcycles, issued a bulletin that from henceforth the physical size of a 15-inch rim for a motorcycle was to be different than the 1-inch rim for an automobile. Why this particular size was chosen, and not others is not known. It can be surmised that this was a popular size for motorcycles in those days. Then it was and so is true today that a standard 15-inch motorcycle rim about one eighth of an inch larger in diameter than a standard 15-inch auto rim.

However, we are leaving out another group of motorcyclists, considerably much larger than the “dark side” motorcyclists, which are really affected by the car-motorcycle tire controversy. That is the international brotherhood of motorcycle sidecarists. These groups, totaling perhaps a million or more, actually need motorcycle tires that are designed for automobiles. They have been around since the beginning of the twentieth century and have enjoyed greater and lesser popularity due to factors such as the base price of an automobile, the availability of the automobile, the consumer interest, and so on. They were extremely popular during the 1910-1914 period, from 1918-1929, from 1948-1965, and so forth. Now, they are driven by those who want the ability of an automobile with the benefits of a motorcycle. Then, as now, they are used to transport a companion (spouse, girlfriend, family member) in reasonable comfort. While they typically have three wheels, two from the tug or motorcycle and one from the sidecar or boat, they are in fact two track vehicles as are cars and trucks. It should not be surprising that these vehicles need tires with characteristics developed for cars for optimum performance and handling.

When turning a sidecar outfit, like an automobile, does not lean into a corner. It remains upright, or nearly so, and so it requires a tread that remains flat or nearly so, when cornering, unlike the solo bike that leans and so requires a curved tire as depicted in the said article. Likewise, the sidecar rig also requires a flexible sidewall to ensure that the tread can in fact remain flat, unlike the solo bike that requires that the sidewalls are stiff.

And this is the contradiction. Where and how? Until the mid-1950s, there was no problem. Motorcycle tires almost looked like automobile tires in design and construction. Even then, some tire makers did develop tires designed primarily for sidecars, and even today a few makers still do in a few of the older popular sizes. But what of the average sidecarist?

Some fitted, or tried to fit 15-inch automobile tires onto fifteen inch motorcycle rims, sometimes with success, but other times with disastrous results. It appears that only the smallest 15-inch auto tires, such as the 15SR125 or 15SR135 can be fitted somewhat fairly easily onto a 15-inch motorcycle rim if one has patience and uses plenty of tire lube. But many of the larger sizes, from 15SR145, 15SR155 and up can and have exploded during fitment, sometimes with physical damage to the persons fitting the tires. It is very dangerous to exceed the maximum pressure rating stamped on the tire even during fitment, and it was not unheard of for persons unaware of the dangers to use as much as 100 psi or more in a vain effort to get the tire beads seated properly onto the rim. There is as much energy stored in a motorcycle tire under pressure as a half a stick of dynamite. Put another way, this is about equivalent to the energy released by dropping a brick from the top of the Empire State Building when it impacts the sidewalk below. The real danger of trying to fit 15-inch auto tires onto a 15-inch motorcycle rim cannot be understated. What happens is that when the tire contains more pressure than it was designed for the steel wires within the tire rim bead begin to slip—they are only held in placed with stiction—and the tire explodes violently from the bead/rim to the outside of the tire. The author had several photos of tires that had exploded in this fashion. Just Google tire explosions if in doubt.

One way sidecarists have resolved the 15-inch problem is to replace the motorcycle rim with a rim designed for automobiles, if of spoked design. Another is to replace the motorcycle wheel with an automobile wheel. Even a tractor wheel. Sidecarists are extremely resourceful.

Note that this does not apply to tires with diameters smaller than 15 inches, or to tires above 15 inches. There one must be aware of other factors such as the width of the tire when inflated within the front or rear forks. As far as what would happen should the sidecarist remove the sidecar and operate the motorcycle with auto tires—this rarely happens. If the sidecarist wants to ride a solo bike then he typically will have another machine set up with motorcycle tires. Once he has converted his rig to operate with auto tires it remains that way and for that purpose. The results are cheaper tires, longer life, and no safety issues if the conversion is done properly.

Another feature of this asymmetrical two-track vehicle is that it handles quite differently when turned into a left-hand curve as it does when a right-hand curve. It is unique in this respect as solo bikes, automobiles, and even trikes turn the same way to the left as they do to the right. The bottom line—there is no right way and no wrong way. Just the way you travel.

Hal Kendall, Sidecar historian, founder USCA



There’s one glaring inaccuracy in the article,
“Predictably, some riders even began to mount car tires on the front rim, as well, and others have followed.”

That’s simply not true. I am not aware of anyone who has mounted a car tire to the front wheel of his or her motorcycle. If you’re referring to those who do what is known as “Double Darksiding,” that is the practice of mounting a rear motorcycle tire to the front of a bike, not a car tire.

The article seems to be a lot of talk and absolutely no action, intended to bolster only one side of the argument—the author’s belief that car tires on the rear of a motorcycle are a bad idea. Instead of writing the article from a desk, how about Rider magazine does some real-world and/or track performance testing to see how a car tire really stacks up to a motorcycle tire? Do the testing that all the manufacturers refuse to do?

Tire and motorcycle manufacturers claim a car tire simply can’t work as well as a motorcycle tire because it wasn’t designed for the task. Riders who actually TRY it claim differently. There’s only one way to resolve it: Test identical bikes with car and motorcycle tires in braking, swerving, and handling tests! Test tire hardness and traction ability between MC and car tires (did you know car tires are SOFTER?) and measure the actual shape and size of the contact patch on a car tire when used on a motorcycle.

I’m not disregarding what the engineers know. The article is correct, they’ve worked hard to ensure the whole motorcycle works as a whole and have designed tires to work well for that task. However, just because something isn’t designed for the specific purpose doesn’t mean it can’t handle the task just as well, if not better in some respects.

After the first rear Metzler ME880 Marathon motorcycle tire on my Kawasaki Vulcan 2000 only lasted 4,500 miles before wearing out (flat in the middle), I researched carefully and decided to try a car tire (General Altimax HP) on my motorcycle two years ago, which I have ridden with for almost 8,000 miles now.

From my research and personal experience, I’ve understood that car tires are designed to take much more weight and much more strenuous forces on a car than they ever experience on a motorcycle. They provide better traction because of their softer rubber compound than a motorcycle tire. While the contact patch gets narrower when the bike is leaned than when the bike is going in a straight line, the sidewall “flexes” to keep a large contact patch on the ground when the bike is leaned over—the contact patch gets longer as it gets narrower, the tire never rides up on the edge or sidewall. I’ve already put almost twice the mileage on this car tire as I got out of the previous motorcycle tire, and have pushed the performance of this tire much harder than I ever did the MC tire. I have yet to be disappointed or find anything it can’t handle.

I challenge Rider magazine to do some thorough investigation of the issue instead of allowing bias to determine the result.

Frank LeClair, Springfield, Oregon



Are you serious? People really put car tires on a motorcycle? Dumbest thing I ever heard of. I think it would be a good thing for you guys to do a story every month on a famous person in cycling such as those found in AMA’s Hall of fame section. Fred Hamm comes to mind. Keep up the great work on a great magazine.

Paul Kerley, Bartonville, Illinois



Thanks for the article on the dark side. I currently ride a Honda Shadow Spirit 1100 and get no LESS than 20,0000 miles on a rear tire. I’m always going to put motorcycle tires on my motorcycle. Ride safe and enjoy every mile.

Greg Wyland, Cameron, North Carolina



I found your article TALES FROM THE DARK SIDE very interesting, and I agree that car tires have no place on a motorcycle.

The one thing you did not address is what affect will car tires have on a three wheeler (all tires being car tires)? I ask this because my brother in law rides a Honda trike, with the same complaint about tire wear.

Hal Steinberg, Simi Valley, California



I just read Eric Trow’s well-written and researched article in the July 2012 issue on the “Dark Side”. It was funny how timely this was. I am a Rider Course Instructor for GWRRA, and we recently had a rider in a course using a car tire on the back of his GL-1800 Gold Wing. I would like permission to share the article with my fellow instructors in GWRRA so they know the information Eric put forth and the reasons why motorcycle tires are different than car tires. Would it be possible to get a .pdf file of the article to share, please? Or perhaps any other format? I don’t expect to convince many of those on the Dark Side—they seem convinced there is nothing wrong with this practice. But if we can keep even one from going over to that side, I think we’ll have made an impact. If you would make it available on your website so we can share the link to it, that would work, too. Thanks for a great moto-mag!

Bruce Thayer, Belleville, Michigan



First of all, I want to thank you for the excellent article you published on using car tires on a motorcycle. I applaud you for taking the time to thoroughly research the topic and present both sides in an objective manner.

One important point I think many folks overlook is not only how the motorcycle tire handles when leaned over due to a motorcycle tire’s profile, but how the bike handles when it encounter a cambered surface on the road, or a rut in the road. A motorcycle tire with a rounded profile will meet the cambered surface and present a rounded edge to the rut or camber in the road, so the motorcycle’s attitude will be unaffected. On the other hand, since a car tire is basically flat, if you ride over a surface of a road that has a sudden camber, tilt, or rut in it, the flat surface of the car tire is going to force the motorcycle to tip in the direction of the camber or will be shifted much more violently by the rut in the road. Many folks who ride with car tires on their bikes have acknowledged that this can make the bike hard to handle when you encounter an uneven road surface. This could be disastrous if encountered in a corner. Many of the roads where I live have large ruts in the surface from heavy trucks and I encounter these frequently. I shiver to think what would happen going over one of these with a car tire mounted to my bike, it’s already bad enough with a motorcycle tire. And yes, I have ridden a motorcycle with a car tire mounted to it, so I know from first-hand experience how they handle and feel, and this is one of the main reasons I’ll never put a car tire on any motorcycle I own. It just isn’t wise.

Fred Harmon via email, Technical Editor, Concours Owners Group (COG)



Good for you, publishing a well-researched article on the pros and cons of riding on a car tire.  Unfortunately, your message, and the message from the informed and educated motorcycling community falls on deaf ears.  The old saying, “A man convinced against his will is of the same opinion still” comes to mind.

At first it seemed odd to me that this phenomenon is peculiar to the Gold Wing riders. Very few owners of other makes employ such a perverse choice for a rear tire.  After conversing with a number of riders who have made the choice to run with a car tire I have found that it is usually for one, or both, of the following reasons: They have a fear of having a blowout, and that a car tire will give them up to 75,000 miles on a single tire. The term “CHEAP” comes to mind, but to each his own. I have seen worse decisions by motorcyclist over the years.

Ron Keys, Ontario, Canada



Using the logic presented in the article concerning the use of automotive tires, the argument could be made that liability exposure could carry over to other modifications such as extended forks, adding a sidecar, pulling a trailer, etc. Any or all of these may be frowned upon by one manufacturer or another but I’ve never heard of a claim being denied due to one of these changes. For a smoother ride, I’m considering an automotive radial for my VTX1300 R as no one makes a bike radial tire in both the front and rear sizes. It wasn’t mentioned, but wouldn’t braking distance theoretically decrease due to the flatter contact patch of car rubber?

As for engineers’ decisions, I question what was thought when putting a wide, fairly flat tread rear tire on, say, a Victory 8 Ball—a bike that does not turn easily due to the tire.

Bill Dennehy, Hanover, MA



I can’t believe you would waste six valuable pages on installing car tires on a motorcycle (RE: Tales from the dark side). I thought it was the April Fools issue. Remember the “War on Drugs” and the “War on Poverty”?  Maybe we should have the “War on Stupidity”.

On the other hand, perhaps the Darwin Awards would apply here. The more riders who install their PepBoy specials on their “Honda-miniums,” the greater the chances of thinning the herd. I would gladly pay greater insurance premiums to clear these clowns off the road.

Guy Ulinskas, Medford, MA



Just read your multi-page Darkside article. Since I’m a Darksider, you cost me some sleep last night thinking about all the bad scenarios you proposed. Only one I think about is if my rear car tire ever goes flat, something that rarely happens to me. By the way, not all MC rear tires have thick sidewalls.  Next time you write an article on a subject you have no real knowledge about (just what if’s) I suggest you ride a Darkside bike/scooter and see what it feels like. Not saying everyone should go this route, but it might give you a different understanding of what it’s about.

Randy Dawes, Kingman, Arizona



I have no problem with a mainstream magazine being against car tires in bike, but responsible journalism means using the facts to make your case. Your writer used half truths and outright made up material to make his case.

I’m done with your magazine. It’s always been third at best anyway.

Todd Ballard, Naperville, Illinois



This is about what is to be expected. I thank God that I live in the USA, where I may add a trike, pull a trailer, add a side car, and run any tire I wish.

Thank you for your time,

Bill Plyler, Advance, North Carolina



I was really surprised to see a person writing an article about something that he has never experienced. I have a 2008 Goldwing  with 38k miles on the odometer. I do about 70 percent of my riding two up. Two years ago on an 18-day trip to Yellowstone National Park, I experienced a tire failure (Dunlap Elite 2). The tire had plenty of tread left on it, it just had a bad vibration coming from the rear of the bike and you could see cracks down in the tire. Thankfully it still held air and the tire was able to make the nearest Honda dealer 59 miles away. The tire that had failed was installed by the local dealer in Oklahoma City and had about 2k miles on the tire before the trip. We were now in Rock Springs, Wyoming with a total of 4k miles on the tire and were having to replace it. I rolled into the local Honda dealer, which, in Rock Spring, also sells cars, I guess because of the limited riding season in that area. They wanted $299 for the tire and that didn’t include installation. So I looked at tire dealers in that area and found a major tire chain that had a car tire that would fit. I had been thinking about this for a while, in fact I saved three car tire-size models and brands that would fit my bike in my phone. I have been on the fence about the change to a car tire for some time now not knowing if I would like the way it rode having it on. I was still undecided when I purchased my last Dunlap Elite 2, which was the fourth motorcycle tire on rear of this bike. Now faced with changing tires again and a nearly $370 price tag, that was the push I needed.  Now Dunlap shouldn’t feel too bad, I still have one of their tires on the rear it was just made for mini cooper. I would like to have a motorcycle tire on my bike, I just can’t find a good heavy-duty touring tire that would hold up to the extra weight of two riders and gear for a long trip and I hate visiting a motorcycle shop on my trips.

I have 15k miles on my Dunlap car tire now and I’m planning another long trip to the west coast. I have no plans of replacing my tire for this trip. It still has lots of meat left on the tire. If I was to guess, I would say the Elite 2 tire failed due to weight. Now with that said, you stated in your article: Which would you trust, the engineers or Joe Bob that said he had good luck running a car tire on his motorcycle. First, engineers send products out all the time that are not up to snuff. This is why we have recalls on everything from toasters to cars and motorcycles and if these motorcycle tire manufactures have been paying close attention to this problem and made a heavier load-rated tire they would have laugh all the way to the bank, but with the problem being ignored and big bike riders having tire failure after tire failure and getting about half of the estimated 10k miles out of a tire, riders started looking for a fix.

Now if you’re on crotch rocket and drag your knee around corners from bar to bar you may get 10k mile out of your tires, unless you’re a burn-out bandit showing off for the ladies. In fact, most riders have to replace tires due to dry rout not wear and tear. I don’t see myself as a mad man, living on the edge living my life testing fate, laughing a face of danger I just want to be able to go on a 4k to 6k mile trip and not have to buy tires before I go and putting a new set on when I return home.

You stated in your article that you talked to motorcycle manufactures and motorcycle tire manufactures, as well as motorcycle safety instructors, and no one would give the OK to put a car tire on a motorcycle. I would think that is because of lawsuits. Let’s say that motorcycle manufacture said to run car tires on our bikes and someone was injured or even killed due to a tire failure, that would open the company up to all kinds of lawsuits. So I don’t think it was a big surprise that anyone you talked to would endorse using a car tire. In fact, I would have been very surprised if they did.

We repurpose things all the time. In fact, we use GPS units on bikes and even put them in covers to protect the electronics from small amounts of weather. Why do people go to the extreme in using a GPS unit that was designed to be inside the car, because of limited choices of weatherproofed GPS units?

You stated that you like people that think differently, but in your cartoon illustration you mock the guy by putting a football helmet, welders gloves, wood shop glasses and loading up his bike like he just returned from a garage sale. It’s too bad that you didn’t do some more digging and talk to a few riders that use car tires and ask what their experience is with both kinds of tires, and Dark Siders that have changed back to motorcycle tires because of the handling characteristics or whatever it maybe. You would have to do a little more legwork, but it would be a fair and unbiased article.

It like, this to writing a article on NASA moon missions. Its cost is too high, or it’s not needed and not safe. Now you write this article without talking to one Astronaut. Let’s talk to only college professors about going to the moon.

The biggest thing about this story is one that you missed totally—the need to put car tires on a bike. The bar hopper will never need these tires and the weekend warrior that may rack up 750 mile on trip will not need these tires, so the vast majority of riders need exactly what motorcycle tire manufacture are making. Surprise, surprise! If Dunlop made a higher load-rated tire with better tread mileage I would buy it, but with a catch. The tire would have to come with a road warranty only because I have heard this song and dance before “this tire has better tread life” ect. And then the tire doesn’t deliver.

It all boils down to the tire being designed for how it’s used. I’m sure you can go out to any parking lot and find pickup trucks with P rated (Passenger) tires on them not LT rated (Light Truck) and if you use your truck to haul beer to the lake or you haul your brothers’ sofa this will work, but if you use your truck to haul rock or pull a heavy trailer you will need a tire that’s up to the task! If these tires are so unsafe, where are all the stories about that? About the guy that dumped it because his car tires lead him astray? The grieving widow that speaks out warning other bikers of the car tire failure dangers? I ride year-round putting around 10-12k miles on my bike every year. I like the Goldwing a lot but it has some things I don’t like, for instance that wicked front-end shimmy. An engineer sent that out the door as well!

I love the magazine. I enjoy seeing the road trip details. I would like to see Eric do a follow up and talk to some Dark Siders.

Kevin Davis, Oklahoma City, Oklahoma



The article was unnecessary, and trivial…. as few riders who use car tires will change because of this article, and frankly, that is a good thing…. the article interferes with “social Darwinism”.  We need to eliminate riders from the genetic pool who are so dumb they do not recognize the validity of the article, and the best was to do this is for them to continue using car tires!

Randy D., Palo Alto, California



I am sure Eric Trow’s article on the Dark Side (car tires on motorcycles) will create a huge storm of letters. I have to say that the article made me think twice about trying one out. I have never put a car tire on a motorcycle, but was considering it.

What I want to know though, is since the liability issue is a prime concern, why does Rider advertise all sorts of items not recommended by the manufacturers, not the least of which are hitches, trailers, aftermarket suspensions, seats, handlebar set backs, cup holders, lights, windshields etc, etc.

None of these are installed by the factory and many, especially hitches and trailers, are specifically NOT recommended.

Is it possible that some items not recommended by the factory are OK, but not others?  Hummmmmmm.

Don Mallinson, Washington, Illinois



Good article on the Dark Side—a popular subject on the FJR Forum. Seems like a lot of guys have no problem with a CT, but for myself I wonder about the times when one needs all the grip possible. Why was there no mention of bead incompatibility and the possibility of running a tire off the rim due to the lower pressure needed to make the tire flex?

G. Schaub via email



After reading Eric Trow’s article on motorcycle tires in the July edition, I think I might be a closet dark sider. I remember 30-something years ago when I was a rookie motorcycle officer and was issued a 1978 Harley FLH Police Special. A total POS by today’s standards but back then I was in love. The bike came equipped with these Goodyear whitewall tires that looked like car tires. Big flat bottoms with car tires tread. They were tube tires, of course, and easily lasted 20k or more miles of police riding. I went through police motorcycle instructor school in Daytona with them where they were subjected to much turning and tight leaning and I was the only one out of 25 students from around the country who never fell during the course. The front and rear tires were exactly the same.

When the rear tire on my 1977 R100/7 wore out, I asked my dealer if there was a tire that I could put some miles on and that dragging the jugs and stuff didn’t matter to me. I mostly rode long distance upright like most people and was tired of buying new expensive tires all the time. He recommended an Avon tire with a flat bottom and car-type tread. He warned it wouldn’t feel like Continental we just removed, but I did not care. I got 20k miles on it and was happy. Although I have never put car tires on a motorcycle, yet, my brother and I talk about it often.

Joe Stein, Niceville, Florida



At the ripe old age of 62 I thought I had seen, heard and read it all, especially when I see one of my neighbors here at my apartment complex ride his bike every time wearing only Bermuda shorts and flip flops, no jacket, shirt, gloves, boots or shoes, eye protection, he has no windshield and in my state (Ohio) it is illegal to ride without eye protection if you don’t have a windshield, nor any other form of riding protection. Then I read “Tales from the Dark Side” in your July issue. It never ceases to amaze me just how stupid people can be. When they have an accident and their insurance won’t pay because their bike did not have the proper tires on it, they will be the first to cry and whine. I guess safety comes last when you want to ride at any cost. In case your wondering, I don’t ride without a helmet, boots, jeans, gloves and jacket except, I will admit, on hot days I don’t wear a jacket.

Martin Feigert, Findlay, Ohio



Please cancel my subscription. This is mainly due to the misinformation spewed forth by Eric Trow in his “Dark Side” car tire article. Did he do the simplest practical investigative technique…like simply riding a bike with a car tire mounted on it? No, he just regurgitated the same garbage as others who have never tried one, state incorrect information. A “double-darksider” DOES NOT mount a car tire on the front…that would be disastrous.

Only a short time ago, it was Chris’s bogus facts and lies about spark plugs…

Please cancel my subscription, as Rider has now lost all credibility with me.

Dean Utendorf, Elmore, Ohio



Bravo Mr. Trow. Bravo.

Billy Max, Minnesota Motorcycle Monthly



I have been using a CT on the back of a Honda VTX 1800C and F for the past 80k miles with no problems. No, a CT should not be used on the bike shown in the article for obvious reasons. Asking industry “experts” about a CT is the same as asking if it is dangerous to exceed the available load capacity of a given motorcycle, something that happens quite often during two-up tests in your magazine. If someone employed in the industry stated a different opinion it could mean the end of a career. Lawyers rule the world. The most dangerous change I made to my 1800F was when I put sportbike pegs on my bike to get a little more lean angle. This caused the side of my boot to touch down first in corners violently sweeping my leg off the pegs.

No, CTs are not for everyone and definitively not for all motorcycles, but for some it is the only way to go.

Steve Silmon, West Monroe, Louisiana



I am greatly concerned about the article in Rider by Eric Trow regarding “Dark Side.” Obviously he has his opinion, one that is shared by many other riders out there who evidently ride predominantly sport bikes, etc.

In his article, he deliberately belittled a very large segment of the most safety conscious riders on the road both in the content and with the cartoon. I have always respected Eric’s opinion and expertise in the past, but this time he is lecturing the motorcycling community about something that he obviously has no experience with.

I have lost three friends riding Goldwings who had rear tire blowouts due to the inferior quality of the rear tires under these heavy powerful bikes. Each of these riders was very experienced and safety conscious, and at least two of them had checked the tire pressures that very morning. Many more have experienced delamination’s, and then there is the loss of grip in the rain, loose gravel, or tar snakes in the corners.

The use of an appropriate car tire creates a much higher load rating as needed by many riders who tour across America for 10-14 hours a day, two up, often pulling a trailer, plus it creates a contact patch some five or more times that of the traditional MT. Even leaned over and scraping the pegs, the tire is still 2/3 in contact with the road and around three times the contact patch of a MT. These tires last more than the 8,000 miles typically gotten from a MT, in fact they usually last around 25,000 to 40,000 miles, meaning that the riders don’t go through two sets of tires in one vacation. Add in the run-flat options and you can see why some of these reasons have become so popular. The CT’s in use are not square (as Eric claimed) but are very curved when mounted and inflated, plus the Goldwing does not lean over anywhere near as far as most other bikes will, therefore they would obviously not be appropriate for use in many other types of bikes.

The manufacturers obviously do not recommend trailers behind a bike, but that is what many Goldwings are doing.

Eric also claimed that many people are also using a CT on the front rim, this is incorrect. “Double Darksiding” refers to using a CT on the rear, and a larger (more durable, deeper tread, higher payload) tire on the front rim. Typically this is a rear tire fitted to the front rim, something that is very common on trikes also.

Dark Siding creates such a positive grip with the road that they can carve the corners faster and more confidently than any bike, save an unloaded crotch rocket in expert hands, plus the rider can stop in much shorter distances, practically standing on the brake pedal, without any fear of the rear tire breaking loose. His claims of reduced braking, swerving ability, or loss of handling are completely unfounded and incorrect.

I suggest that Eric get in touch with some owners who are Dark Siders, ride their bikes and get some experience himself before slamming a practice that has had zero deaths, zero injuries, zero insurance claims refused, and zero blowouts (in the case of the run flat tires) or delaminated tires—even with over 10,000 riders successfully putting on millions of serious miles successfully using them.

I do not recommend the Dark Side to anyone, instead each person must study the options and then choose for themselves, but the practice is very common among Goldwing and Valyrie owners. Some CT’s have also been used on bikes dating back to the 1920’s with great success.

Ray Skyes, Oceanside, California



The article by Eric Trow on the car tire issue was so one-sided I thought he had been working for the government helmet data team.

My friend in Missouri has a Valkyrie that he was having tire wear issues with and after talking to other Valkyrie riders he installed the dreaded car tire and runs at 45# air.

It is a performance-type tire. I have followed him on rides on the Missouri Ozark area roads riding his spare Valkyrie and watched his rear tire. When in the curve, there is still more tire on the pavement than any motorcycle tire except maybe the 205 and Larger Avon’s.

He also put a car tire on his spare Valkyrie since he had not any problems with the car tire on his main bike. I have ridden his spare Valerie with the car tire on it and it rides and handles just as good as with the cycle tire.

May be Eric should have been a good enough reporter/writer/rider to find a bike to try for himself and then write the article. I know the liability issues for you to say, oh use this tire, and of course your advertisers are selling cycle tires. Remember that these are being used on the larger bikes. As for my V8 Kannon bike with a 205 Avon I see no difference in handling between his and mine, so guess what tire I am going to put on next?

I will be going dark!

Brad Schiller, Iowa



Let me preface this by saying that I do not condone the use of car tires on motorcycles for the reasons stated by the “alleged “experts quoted in the article.

The use of car tires on motorcycles is nothing new…Goldwing owners have been doing it since the late 1980s. Mr. Trow never heard of using a car tire before? How long has he been riding? No one would be mounting car tires on motorcycles if the motorcycle tire industry produced a tire with acceptable wear characteristics. Mr. Trow’s statement that motorcycles tires wear like performance car tires is an outright false statement. Performance street tires for a car last 20,000…you would be lucky to get 10,000 miles out of most motorcycle tires. I would cheerfully pay 50 percent more for a tire that lasted 50 percent longer. I assure you as soon as ONE motorcycle tire manufacture steps up to the plate and manufactures a tire that will last 25,000 miles the rest will follow.

It is grossly inappropriate for Rider magazine or the writer to offer “legal” opinions in this matter. Should Rider magazine, the writer and tire manufacturer be held liable when someone who has taken his safety class using tires approved by them takes a tumble?

Andy Kollar via email



I agree that putting auto tires on bikes is probably not a good idea with one exception: the increasingly popular trikes. They are basically three-wheeled cars, so car tires should be perfectly OK. On the problem of under inflation, the cycle manufacturers bear a lot of blame for this as tire stems on many bikes/scooters are almost unreachable, particularly in the rear. On my late and unlamented Goldwing, I had to lie flat on my ass to get to the valve. Many bikes no longer have center stands, which makes tire inflation even more taxing. Also many bikes do not have angled valve stems; again making access difficult.

I have six cars and three two-wheelers and the bike tires lose air much more rapidly than the car tires. Why can’t the bike and tire manufacturers not produce tire/rim combinations with air retention equal to autos? One of my vehicles has Michelin high-performance tires that lose about two pounds per year! I can over-inflate them by two pounds and not worry about them for two years.

Jack Page, Germantown, Tennessee



I’m very disappointed in your article concerning the use of car tires on large touring bikes. Have you ever ridden a Gold Wing with a car tire? Have your quoted experts?

If so much time is devoted to design, why does the motorcycle tire change shape (permanently) in the first few thousand miles becoming flat across most of the tire surface and resembling a car tire more than a new motorcycle tire? I don’t know how else to say it but the eraser example is not accurate. I have never seen any tire with sidewalls straight to the flat tire surface (check out the sidewall of a Bridgestone Potenza g019 Grid, deep long curved sidewall groves). I also don’t see the relation between medical professions and tires.

The proof is in the doing. I and many of my personal friends have accumulated hundred’s of thousand’s of miles using car tires on Gold Wings (with zero failures). The Gold Wing and large touring bikes may be uniquely suited to car tires due to their extreme weight. I have personally ridden my Wing (with a trailer) on the Dragon, putting footpegs to ground on both sides with no ill effects or sluggish response in handling.

We started using car tires for safety purposes because the motorcycle tires would delaminate, it’s not fun to be two up with a trailer and have the back end start dancing because the tire delamanated, long before reaching the tread bars. After the third episode, I contacted the manufacturer and was told the motorcycle tires were not designed to run in extreme heat or pulling a trailer. Well, the car tires handle it just fine. They run cooler, run longer, have a greater braking surface, are rated to carry more weight and they handle equally (even better when the motorcycle tire goes south) to the motorcycle tire. The possible exception may be in racing conditions…we don’t race Gold Wings.

The fact is that a lot (if not most) touring riders overload occasionally and many do pull trailers (just check all the trailer manufacturers and hitch makers). It’s not all about the money as many would not run anything but a run-flat tire and most of those cost as much or more than a motorcycle tire. It would be great if the motorcycle tire makers (and their knowledgeable engineering staff) would step up, but until that time it seems like we’re on our own.

Again I think you should have at least tried it in a controlled environment before condemning the use of car tires. Or simply not addressed the issue at all if you have no real experience with it. I generally respect your opinion when it is really your opinion and not a consensus arrived at by a team of slide rule jockeys that never tried it or tried to fix the problems with their tires.

I do like your magazine and enjoy your column each month. There’s no need to reply I just needed to vent some frustration with the tire safety issue.

The insurance scare issue is bunk. Talk about liability…what about all the companies that make modifications to motorcycles (trailers, trikes, hitches, modified lighting, suspension changes, on and on and on). And speaking of liability, what did you think the motorcycle tire manufacturers and other experts were going to say in print!

Bill Shartzer via email



  1. To Gary Ulinskas,Please write back with the brand bike you ride so all of us can be on the right one. Are you riding a BMW?

  2. I am currently on a 14,0000 mile motorcycle tour of America. I am doing this tour on a Michelin Primacy Alpin “Car Tire” mounted to the rear of my 2012 Goldwing, my 7th Wing, with an Escapade trailer in tow.

    I used to post on motorcycle forums about how a CT was “a bad idea … unsafe … in violation of the tire’s design intent”, etc. I posted a LOT of nonsense, because all of it came from a man who NEVER RODE ON ONE prior to posting. I was responding based entirely on conclusions I had reached, formulated out of nothing but assumptions. I discovered that nearly all of the anti-CT folks are doing the same thing, apparently including the author of the RIDER Magazine article.

    Well, a visit to a good friend in Georgia changed my mind. He had this tire mounted to a wheel. I accepted his offer to mount that CT to my bike and “take it for a ride through the Georgia twisties for a while.” It only took me about 10 minutes to realize how glaring my ignorance in those posts was, to those “in the know.” The Darkside Riders, (among whom I am proud to now count myself!) probably shook their heads at reading my posts, knowing that I knew NOTHING about the subject. To all of them, please accept my apology!

    I NEVER felt more confident in turns, crossing diagonal railroad tracks and while riding in every road condition I could hunt down, including “road snakes” and gravel. I was diving into turns at 60 that I would otherwise have approached at 40 with caution, and all the bike kept telling me through the handling feedback was, “GIVE ME MORE!” I had no indication that the tire would slide out from beneath me while I turned the corner on the edge of the “square” tire.

    I’m NOT an inexperienced rider, having nearly 600,000 miles under my belt over 26 years. I used to ride for motorcycle courier services in southern California, and I was a “transfer driver” for Ryder Truck Rentals, using a Goldwing to move trucks from point-A to point-B. Chalk up countless miles riding with the clubs, and riding into the night after riding all day at work, just because I love to ride!

    People get hung up on the word “car” in the tire’s description, however, nothing on the actual tire reads “CAR tire.” Assumptions about CTs on motorcycles stem from mental images of running the old ply tires we used to mount onto the 60’s era Chevy Bel-Aires and Ford LTDs. “When you lean the bike, the tire will ride up on a thin, square edge! The sidewalls will buckle! The tread will lose its grip! The plies will separate!”

    Like everything else, tire technology has changed over the past several DECADES. Today’s CTs are nothing like their 60s and 70s era predecessors. My NEW Michelin Primacy Alpin so closely resembled the profile of a Dunlop Elite with 6,000 miles on it, that I had to wonder why touring motorcycle tires aren’t designed EXACTLY like this tire. Their shape was nearly the same, except that the Michelin with it’s “flat center” had nearly 5/8″ of tread on it’s “flat center”, while my old Goldwing tire with an embarrassingly low 6K miles on it was nearing the tread wear bars already.

    My Michelin is a ZP (Zero Pressure) or RF (Run Flat) tire, which means that the sidewalls are VERY stiff, and IF the tire goes flat, it will not buckle and flop around the wheel while one tries to bring the bike to a stop like nearly ALL of the motorcycle tires will. Since a touring bike spends roughly 95% of its time riding straight up, a round tire is only forcing the rider to START OUT on a thinner strip of rubber, until the tire wears down and puts more rubber onto the pavement.

    A mechanic rode my bike at a Honda dealer. Oh, he argued about how the CT would give the rider a “hump” to ride over. He said the bike would have to be “pulled” up over the edge to make a turn ,,, and the bike would handle funny when it was brought back up to vertical “on the flat center”… blah blah … until he RODE a CT mounted to my bike. When he returned, the very first thing he said was, “You’re right. you CANNOT feel the shape of the tire going into, or coming out of a turn. It feels just like a round motorcycle tire!” Gosh, imagine that. An opinion coming from someone that actually RODE a CT, and someone who was vehemently opposed to the concept only moments ago. He was nothing short of impressed by the feel.

    The arguments about the bead match and all are just more uninformed assumptions. My CT now has 6,000 miles on it, and the tread is well defined, and in great shape! Sorry folks, but I am not seeing reports of motorcycle crashes CAUSED BY a CT being mounted to the bike. Crashed bikes that just happen to have CTs mounted to them are meaningless. One could as easily say that the bike crashed because the rider mounted a “boat” cup holder, as it had nothing to do with the crash. However, as the former owner of a motorcycle towing service in southern California for 13 years, I will continue to ride CTs on my TOURING bikes, because I am now speaking from EXPERIENCE, not from assumptions.

  3. Thank you for posting my letter about the Dark Side on your website. From the letters I see here and at various owners websites this debate inflames passions like no other in the MC community. Sad. The non-motorcycling wishes us way too much misfortune for us brothers and sisters to cannibalize each other. Most of us on the Dark Side just wished Rider had tested the Dark Side no differently than you would have the newest from XYZ Motorcycles and given us your honest opinion.

  4. After actually reading the article, I have concluded that the “unbiased” claim was bogus. The line, “Still not convinced?” certainly reveals the true intent of the article. I have followed the responses because I am now approaching 10,000 on my Michelin Primacy Alpin tire, and judging from the tire’s appearance and remaining tread depth, I probably have another 12-15,000 miles of life left in the tire before I need to worry about replacing it.

    Lots of assumptions, and the selective presentation (and omission) of facts makes for a good article, if only for its entertainment value. Why did the author leave out the fact that the car tire is meant to carry a load roughly FOUR TIMES that placed upon it while mounted to a motorcycle? When the bike leans, the assumption is that the sidewalls buckle, because they WOULD buckle with the weight of a CAR placed upon the tire at that angle. A motorcycle (my Goldwing) puts about 500 lb. of weight on the rear tire in the vertical position, and slightly more via different dynamics while in a turn. Why should a car tire fail, when it is only asked to support roughly 1/4 to 1/3 of its rated load?

    Why were no photos of a car tire presented? You Tube contains a myriad of videos made by Darkside Riders, showing the actual performance and handling of car tires mounted to Goldwings and other bikes. They mount cameras right down at the tire, to record the tire’s contact with the road during a spirited ride. Watching the videos will dispel any notion that the car tire rides up on a “thin edge” during a turn. The sidewall flexes slightly, but the contact patch is FAR from resembling a “thin line” of rubber.

    The claim of tires exploding during mounting due to excessive pressure required to seat the bead are as invalid and unsubstantiated as claims of insurance companies denying claims due to a car tire mounted to a motorcycle. The truth is that they would pay the claim, although they might refuse to continue to insure the rider until an inspection of his bike showed that he was riding “approved” tires. For them to deny the claim, they would have to PROVE that the car tire was directly responsible for the crash or at least a major contributing factor, and as the author must know, there is NO DATA to support such a claim. Only assumptions and innuendos.

    I’d like to see any HARD DATA showing the percentage of modern car tires that have exploded during mounting, due to excessive pressures used to seat the bead. I suspect the fears stem from stories of the old truck tires with split rims, that were inflated in large steel cages to contain the explosion when the lock ring slips around 80 p.s.i.

    It is true that the low speed tracking of a car tire is “different” than a round tire in certain specific situations, especially at intersections where small towns seem to ignore deep truck tire ruts in soft asphalt. In that situation, the bike does want to “tip” a bit, but it is not uncontrollable, and certainly not a big concern for a rider who pays attention to what his bike is doing. I also noticed a difference while crossing a grated metal bridge. The tire seemed to track differently. “Differently,” but not better or worse. There was no “Uh Oh!” moment. I simply noticed that the car tire has more of a grip on the metal grating than a motorcycle tire does.

    I would very much like to see a head-to-head REAL WORLD test of a car tire in the next issue. Get two identical Goldwings. One with the traditional motorcycle tire, and the other with a car tire that is SPECIFICALLY ENDORSED by the Darkside Riders. Don’t mount up a “Pep Boys Special” car tire and then claim to have performed a valid comparison. I suggest the car tire mentioned above. Get two talented riders, and take them for a spirited ride through the twisties. Publish the results of your findings.

      • My first Ct was the Michelin Primacy Alpin, so I cannot compare it to the Bridgestone per your inquiry. I can tell you that I consulted with many darkside riders before choosing the Michelin tire, and I will stay with that make and model until such time as the others suggest a better alternative.


  5. Here is one more fact to consider. The article pointed out that a very small percentage of touring bike riders have chosen “The Dark Side” and this is offered as evidence of the folly that accompanies the decision. Lets look at the numbers from a different perspective. Of ALL of the riders who have actually TRIED a car tire on the rear of their Goldwings and other bikes, roughly 99.5% of them are PLEASED with their decision and would resist returning to a motorcycle tire. I am Darkside Rider #1238. I have followed the posts on message forums that discuss this practice, and I can safely say that in the past nine or ten months of reading countless PRO-Darkside posts, I have stumbled upon only TWO threads started by persons who tried it and did not like it. You can do anything with numbers. When you compare car tire riders to all motorcyclists, they are a very small, insignificant segment of the riding community. When you compare the number of people who have tried a car tire to the number of people who are still riding on a car tire BY CHOICE, you have a more concise set of numbers to examine.

  6. I agree with bill , lets see a real test. Not just hear say . It may just go the way of your motorcycle tire advertisers! But then again may not.

  7. Greater amounts of ethanol affects more than just motorcycles and small engines. My wife and I, have a 2012 Honda Fit that states in the owners manual no more than 10% ethanol content in the gas used.

  8. Thanks for reprinting the article on the physics of auto and bike tires.
    Now comes the next step challenge, “what about trikes”? The manufacturer of the Roadsmith trike kit recommends mounting the front tire “backwards”. To date, the explanation as to why is not clear. A Michelin Power pilot has a harmonic and the tread can be heard below 10MPH. (tried a replacement: same thing)
    Putting that aside and now understanding the engineering differences between auto and bike tires, it leads me to conclude that trikes could and should use a car tire as the front tire. Given and trike does not lean and there would be a much larger contact patch, which would seemingly enhance the braking performance of a trike. Which as we know has much greater mass to stop. I have to imagine it may even require less “pedal” pressure in what previously were full “fisted” stops. Would it also extend brake life?
    What do you think?

  9. Idiots. The “total number of miles” (wear) is an irrelevant claim (non-applicable) to safety. Do you buy cheap helmets for the same reason? Or do you ride with quality gear that cost more? When I read a supporters claim about “miles achieved” I just shake my head. These people are allowing their budgets to dictate their decisions about what they need. Most supporters of car tires on motorcycles all seem to be riding road-wrinkling poor-cornering machines. If this is true (as suggested by all the posts, stories and claims I’ve now read) then their anecdotal “evidence” is useless for 90% of the riders that take corners at speed. This is a good article about how car tires and motorcycle tires are supposed to work – and what they are really designed to do – recommended reading for everyone interested in this ridiculous ‘debate’:

    • Running Ct for years on goldwing1800 .I cannot speak for other bikes but on mine I am pulling a motorcycle camper with equipment and provisions for 4 to 25 days of camping most of the time . I believe the two most important things I need to be concerned with are , with a heavy touring bike blow outs. And braking. The car tire exceeds motorcycle tires leaps and bounds in both , I run 34 pounds air. I have more rubber on the road even when leaning. Some say cheap . I say I have more money to take a trip . Also think about places your at that do not have motorcycle tires you need . The cost is I third of a motorcycle tire givin cost and mileage of the Ct. Ok now the cons if you need some. Yes Ct amplify the ruts in roads more than MT not a lot but more. When you take your first ride on Ct it feels like you have to much air in it . ( you will get use to it quickly) also when your buddy’s can’t get there campers up a wet grassy hill You will have to pull them . One more con. Heavy rains. Ct are great. But the guys that are constantly downgrading us using Ct. are not pulling trailers or haveing to mount 4 Rear motorcycle tires a year. If I just road. Around local 3000 or 4000 miles a year with no camper in tow. –I might use a mt. But I don’t. And the word cheap has nothing to do with it . How bout those Cowboys!!

    • Not just miles achieved but those achieved without life threatening catastrophic failure. As pertaining to the delamination and blowouts occurring with typical motorcycle tires that end up being overloaded or over worked pulling trailers and such. Not everyone rides one up carving corners on a 400lb rice rocket with 240 or wider rear tires. Some take their touring very seriously. And others belong to the brotherhood of the third wheel or ride seriously beastly bikes. All of which reliably and safely use CT’s on their rides. As an occasional V8 trike / bike builder / rider I do constantly. As even the front of my most rides weigh in excess of 600 lbs and considering weight transfer during acceleration and breaking it is pretty much mandatory to obtain any semblance of a reliable safe ride.

  10. John
    so … you are one of those who ridicule others … without actually trying it.
    i guess i would have to say … you are the idiot.

  11. Being a Darksider is like joining a cult. Their strong group affiliation makes them immune to reason.

    I wanted to try a car tire to see if it really was better as they all claim. I kept an open mind, and really did want it to be better so I could reap the mileage benefits along with all the other claimed benefits. So I tested my motorcycle specific tire first. I went through wet areas to dry while turning so measure the contact patch width. And I did a full lock rear brake only skid to a stop to see if they really do have more stopping traction(I did full lock to make sure both tests were identical).

    After putting on the car tire, I repeated the tests, and took pictures. The contact patch on a leaning turn was actually bigger with the bike tire. And I had pictures to prove it. On the lock up stop, the car tire skidded further taking longer to stop. And I rode my large displacement V-twin in the dirt fairly often too. Gong up steep loose traction hills in dirt and rock that had been no problem with the bike tire, were worse with the car tire. The car tire spun and lost traction easier than bike tire did. Not intuitive unless you understand physics.

    So even though I wanted to prove that the car tire was better in every way, it was worse in every way.

    All my photos and measurements did nothing to persuade the Darksiders. They blamed my tire choice. My inflation pressure, etc. etc. Blaming them even before knowing what they were mind you.

    The Darksiders feel what they want to feel. So the feel braking that is sooo much better etc. etc. Without ever actually measuring it. Reason will not break through their desire to belong to an exclusive club that is smarter than the rest of us. It is a cult by this point I think.

    • For one, measuring breaking distance is not done by locking the rear wheel. Once you lose traction, that’s it. However, the car tire should have, in a skid, cone to a stop in a shorter distance due to the larger contract patch with the ground, physics. If it did not, then more than likely the tire was overinflated.

  12. I now am the owner of a 2017 wing am planning a cross county trip this summer was wondering if anyone has tried using nitrogen in their tires and what the effects would be on the tps. I know from experience that in heavy duty truck tires you get longer thread life and less pressure loss over time

  13. I just put a 205 60 16 on my 08 vtx1800n I have gone to the dark side thank you all for good info Ken sasser

  14. Well, did you guys ever take the challenge & do the tests or not? The dark side guys did. Aren’t you better then they? Don’t you have more test equipment than they do? They are the amateurs aren’t you the professionals? Could it be that you’re afraid of the findings? Or of admitting you were wrong? Some times we all have to eat a piece of humble pie or crow. So, how about it? If you do this & your findings are negative & you can with real life testing PROVE they are as bad as you & others say they are. What a powerful punch that would be. If not, yours is only untested opinions & theories with out any FACTS. According to the laws of aerodynamics the bumble bee cannot fly, but of course he tried it anyway and is doing nicely. By the way I DON’T run car tires on my GL1500…at least not yet. I ride 20-30k every year& passed 500k 20 years ago so I’m no newbie. Convince me not to run a CT on my mount, but with real life testing.
    Still, you guys are the best in the business.

  15. After riding my wing around thirty thousand miles with three or four flat tires I went to a run flat car tire. Pireli. I have 125 miles now with car tires. No flats. I ride twistiest scraping the pegs and I get better traction than a bike tire. I am on my fifth. Car tire. No flats. Or I buy another bike the first thing I will do is change to a car tire. Motorcycles tires suck and your lack of on bike testing you should have just kept your mouth shot as you are not qualified to write an article. After riding thru ruts are the only thing you have to get used to. Pay attention and tge ruts are not noticeable. I’m like in the eighties in the darksiders. Never run a motorcycle. And you bs Ed about the front tire. People don’t run a car tire on the front. Some were running bias plied trying to get more miles. Problem is the bias ply shimmies after a few thousand miles. But they still work. I threw it away after about six thousand miles I like a smooth ride. Car tires forever.

  16. After reading a good mango’s these comments, I realize that of the critics of using cartires on a motorcycle, none actually had personal experience in riding a motorcycle with a cartire on the rear.
    With all the commentary in support of using cartires by actual users, I can only conclude that you are afraid to lose advertisers of motorcycle tires if you actually do a serious test of this yourself.
    If you were into serious unbiased research you would have done so already. Disappointing and hypocritical.


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