Is It Worth A Try?
It’s a new year, so let’s visit an old controversy! As motorcycle riders, we’re always looking for ways to enhance the ride, both the bike and the experience. We’re keenly conscious of costs as well, as our passion can get quite pricey. Enhancement versus economy- its a tightrope to walk (or ride), for sure.
We’ve done a fair amount of tire testing in the last couple of years, with Ted Edwards and Dave Wensveen logging thousands of miles across the western states. One unconventional option that we’ve never tried but still fuels debate in some circles is using automotive tires on motorcycles. While motorcycle tires are specifically designed for the unique demands of two-wheeled vehicles, some riders still think it’s worth exploring the possibility of installing car tires on their bikes. Most of us respond with, “Are you nuts?!” Yet we still occasionally meet riders who swear by them. My friend Ken Glassman and I were recently discussing this as well. So, let’s take a deep dive into the pros and cons of using automotive tires on motorcycles, and see where we can park this debate.
Car tire mounted on a motorcycle. Looks harmless enough,… photo by Inside Motorcycles.
When talking with proponents of automotive tires on motorbikes, here’s a few of their “pro” arguments.
Cost Savings:
One of the primary motivations for using automotive tires on motorcycles is cost savings. Car tires are generally more affordable than motorcycle tires, making them an attractive option for some riders on a budget. The larger production volume and variety of car tires also contribute to a wider range of budget-friendly options. So, those who “ride the dark side” swear this makes them a viable option.
Longevity:
Automotive tires are typically designed to endure greater mileage than motorcycle tires. The added durability and overall design difference of car tires obviously results in a longer lifespan, meaning riders don’t have to replace them as frequently. This can be particularly appealing for those who embark on long-distance rides or use their motorcycles for commuting purposes. I had a friend who rode a Honda Goldwing that he shod the rear with a car tire, and swore he got 30+ thousand miles out of them at a fraction of the cost of more expensive and more frequently replaced motorcycle tires.
Stability and Traction:
Some riders argue that car tires provide greater stability and traction, especially in wet or slippery conditions. The broader contact patch of automotive tires may enhance grip on the road, potentially improving overall handling and performance. In a straight line. But in a full lean?
Bike in full lean, rear auto tire tread and contact patch clearly visible. Your thoughts? Photo from Iron Butt Forum.
Let’s look at the reasons car tires are NOT a good idea on motorcycles.
Handling and Maneuverability:
Motorcycles are engineered with specific tire characteristics in mind to optimize handling and maneuverability. We’re on two wheels, not four, so obviously the handling characteristics are completely different. We’re leaning motorcycles, not steering them. Automotive tires, designed for three and four-wheeled vehicles, simply cannot offer the same responsiveness and agility as motorcycle tires. This leads to a less precise and more cumbersome riding experience when installed on a motorcycle. And potentially dangerous.
Compatibility:
The overwhelming number of motorcycles are definitely not compatible with automotive tires. They are each designed for completely different types of riding/driving. The rounded construction of motorcycle tires works perfectly with the front/rear wheel design of motorcycles, making diving through corners nearly effortless. The squared profiles of automotive tires are clearly designed for a tri or quad setup on a vehicle, working together for maximum contact with the surface. My friend Mike owned a Harley Tri-Glide with automotive tires on the rear, which works great for a trike as well as a four-wheeled automobile. His Honda NC750X however runs Bridgestone Battlax A41 Adventure tires for on and mild off-road riding, which of course is what these tires are designed for.
Legal and Safety Concerns:
In many regions, using automotive tires on motorcycles violate safety regulations, insurance requirements and/or manufacturer recommendations. This can have legal consequences, and insurance coverage may be affected in the event of an accident. Riders should thoroughly research and understand the legal implications before opting for car tires on their motorcycles. Is it really worth the supposed cost savings and tire life gains?
Closeup of car tire mounted to a bike, on kickstand. Interesting. Photo posted on Quora.
While the idea of using automotive tires on motorcycles may seem tempting due to potential cost savings, longevity and other perceived benefits, riders must weigh the pros and cons carefully. Safety should always be a top priority, and any modifications to a motorcycle really should align with manufacturer guidelines and legal regulations. Before making the switch to “the dark side” as proponents like to call it, you should consult with professionals, conduct your own thorough research, and ensure compatibility to maintain a safe and enjoyable riding experience.
Our opinion? If motorcycle manufacturers thought auto tires were a great idea, they’d build bikes with them in mind, and would install them on their two-wheeled machines from the factory. But they are not compatible and not worth the effort or risk, in our humble opinion. We’ll never use them nor will we ever recommend them. But that’s just us. You do you, friends.
What are your thoughts on the subject? Let us know in the comments below!
Rob
Funny cartoon from years ago, posted by Rider Magazine. Sorry, we couldn’t resist.
My brother-in-law first convinced me to try a Goldwing after years on an H-D. He later convinced me to go darkside on it. I did and after very little riding on it, I was sold. I’ve run the mountains (Tail of the Dragon, etc) and run long distance while towing heavily laden camping trailers. I have nothing technical to offer, other than to say I’m quite happy with it.
Do you find any handling issues either at slow speeds, or in tighter corners?
So I own a Triumph Bonneville T100 with a Cozy sidecar and I would LOVE to install car tires on it. My question is, can I find car tires to fit the stock 19″ front and sidecar rims and the rear 17″ rim? I’ve searched and can only find emergency spare tires in those sizes. I am aware that the classic sidecar thing is to have car type rims laced up to your motorcycle hubs, for something like 15 inch VW Beetle tires. Obviously I am trying to avoid that cost. Also, flat car tires are ok on sidecar rigs since no leaning is involved while riding.
Hi Dwayne,
We’ve not taken a deeper dive into “the dark side” beyond our research for this story. We know there are forums out there pertaining to it, and apparently social media groups dedicated to it.
It’s not our thing, obviously, but we’re sure you can find sources to answer those questions.
Thanks for joining in the conversation!
Back in my younger days I owned a 1970 Honda 750-4. When I bought it still had the original tires on it. The rear was somewhat square, flat tread, like a car tire. Bike handled terribly in the curves. Soon after I had the tires replaced with a more modern rounded tire. Huge difference!!. Bike handled so much better in the curves, the way it should. I now ride a Yamaha fjr1300 and there’s no way I’m ever putting a car tire on. I’m not compromising safety and handling. Not worth it me.
Agreed.
That’s me in the photo. I have over 200k miles running car tires on FJR1300s. It works for me. Your example is not a good one. I too hate the handling characteristics of a ‘squared off’ motorcycle tire. Running a car tire does not have those negative attributes. There are definitely differences, and it is not for everyone, but really, it’s not that bad.
Thanks for sharing your experience, SkooterRG.
Hi Rob! You know I double dark sided my bike for quite a few years. It was cool and interesting to try. Some extra thought on this and why I went back to motorcycle tires eventually. Instability issues can happen. Front tires are self aligned to the rear tire. So having a wide rear contact patch can cause the front tire to hunt for the center of the rear tire patch. This shows itself in handlebar feedback. As the bike transitions into a turn the front tire adjusts and when you get used to it, the initial unsettling feeling becomes the new norm. However when traveling on parallel uneven surfaces the bike can become a bit unsettled in its track. Tire bead and sidewall construction are very different than a motorcycle tire. I had decent results with tires designed to deliver better gas mileage as they have a stiffer sidewall. However to keep from being too long winded, I went back to motorcycle tires for this reason. Think about the difference between worn out motorcycle tires and a brand new set. The new ones are fresh, they handle great and you corner with confidence again. Now go back and look at the old rear tire. Most of the wear is in the center. So why is a 1.5” bald patch so terrible compared to that fresh new bike tire? And now think about why you would want to install 5” of that from the beginning with a car tire! We ride bikes for enjoyment not to save money! Otherwise we would do it on a scooter that got 100 mpg.
That is VERY well-stated, Phil. Thanks for a fantastic explanation.
Funny it is mentioned scooter riders doing what they do “just to save money… really?”
There are actually scooter riders who use a car tire on their scooters too! (for several reasons) There is an interesting piece here :
https://mcdarksiders.forumotion.com/t7188-for-maxi-scooters-the-darkside-according-to-bandito2-part-1-2
Hello Rob! I had a riding buddy who dark sided his FJ1300 and he loved it. The savings were quite substantial and the mileage was more than amazing, up to 5 or 6 times what I got on my Dunlops or Michelins. He did a lot of commuting and highway riding which take full advantage of the wide and flat tire profile. The thing that almost pushed me over the edge is that I have gone through 2 sets of premium motorcycle tires in a single season several times. I have never gotten over 7000 miles on a set and have sometimes had to change out at 6000 miles. And these were pilot road 3’s or roadsmart 4’s(hi dollar and supposedly higher mileage tires). Now, every other season, the tire manufacturers come out with their new compounds and tread designs (with what seems like less real tire materials or side wall strength) for more and more money. So, given the mileage and high tire cost, it’s hard to keep up with the demand on my credit card! I have friends who can get almost twice the miles on a set of premium tires, but they don’t ride the same way I do. If you ride your bike trying to get all of it’s potential into your ride, like I do, then the dark side is a dangerous place for you to go. If you ride like my FJ1300 buddy, it can be a nice option to save lots of money and tire changes. I have to laugh whenever I’m following a dark sider…. When they turn, all I can picture is a dog hiked up next to a fire hydrant 😆
Hi Steve!
Great thoughts, and yes, I agree, kinda strange riding behind one, for sure.
We should visit and chat again soon!
Steve Hawkins said: “If you ride your bike trying to get all of it’s potential into your ride, like I do, then the dark side is a dangerous place for you to go.”
Listen, I am not trying to convince you to Darkside, nor that it is for everyone. And people have different experiences with the same equipment. But, I do take exception to that statement. I can easily scrape the pegs on my FJR1300 with a car tire out back and have done so many times. It is not a dangerous place to go.
I asked users LOTS of questions over 2 years before deciding to go Darkside. Once I road a dozen or so miles I became acclimated to the different feel, which was rather minimal. The only riding difference was the turns, to me the bikes rear did turn slightly (others call it going straight) but I used it to my advantage. I steered my turns a little less since the back slightly pivoted. You know some Honda cars rear wheels pivot their turns without issue? Once I was hooked I went DDS (Double DarkSide rear bike tire up front).
SO… stopping was simply amazing, IT… WAS… QUICK!!! Had to start looking behind me before stopping to make sure THEY were paying attention. To be safe I accustomed myself with stopping nearer to either side of the lane AND pointing the bike outward JUST IN CASE I needed to scoot over a few inches from being rear ended. Which happened once so far but by moving a mere foot or so over, the mini truck softly plowed into the car I was behind.
The DDS tread patch width on the road was nearly doubled, rear & front had 1.75% more rubber on the road. In turns I measured the tire patch at about 1.67% more than bike tires. How did I measure? Rode slowly through a parking lot water puddle upright then in a well leaned turn.
Overall cost was lower by 1/3 less and longevity was quite a bit higher by nearly doubled up front (about 195%), the rear about 550%. I used Austone Taxi tire and got 80,000 miles 3 times in a row. Yup 240,000 miles on just 3 rear tires. If I used normal bike tires I would have needed 20 to achieve 240,000 miles (I averaged ~12,000 miles on bike tires).
OK… now for the tire bead difference. Yes there is one, while I never had a flat rear car tire I cannot vouch for said car tire jumping over the “inner rim bead” but I will say installing said car tire on a bike rim that inner bead absolutely need lubrication… it is that tight! Sealing car tire bead to a bike rim. Yes it does seal but at minimum about 90% (tire mfg depending). Is it enough? Yes, I say it is. I had a car hit my trailers rear tossing my bike at expressway speed and sent the bike into a SEVERE wobble where I eventually HAD TO depart off the bike or go over the railing & onto the Tollway below. Shortened story, went to pick up the bike & trailer next day at the towing lot, neither tire never lost one PSI.
LASTLY (yaaaay) IF you never rode DarkSide you have absolutely no experience of how well it works. All you’re doing is explaining like a bookworm would. In that sense, you don’t use common sense. Naysayers, ask yourself, why are we not still living in caves?
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Thanks for sharing your testimonial and experiences, Vern.
Thank you for recognizing it.
This article sorta reads like it’s biased against DarkSiding, true or false?
_One of my many questions B4 changing was how many crashes were caused by car tires on bikes, none. I then went back in modern times (1990 to present) asking the possible accumulation of DarkSide miles on all bikes. While the answer isn’t exact, we came up with (2010-ish) well over a Billion accident free miles. It was that answer that convinced me to try it.
You are correct, Vern, the article does not endorse it. We are, however, open to the conversation. Thanks for sharing your calculated thoughts on it. The discussion is why we published it.
I ran a car tire on my ’17 FLTRU FOR 100 miles a couple years ago 2-up, and couldn’t stop it from wandering. It always felt squirrelly no matter road surface or condition. 30 up to 70 psi, not fun. Bridgestone all season radial. Maybe should have tried a dual sidewall ‘run-flat’ model.
The stopping too quickly thing… I can grab a good handful of front brake and a little rear brake and stop quick enough that it feels like doing your 50th pushup on your arms. That’s using motorcycle tires, and on several different bikes throughout the years. Besides screwing around riding on the front tire “stunting” in my very very early days, I only have stopped that quickly in emergency situations like deer running out or a car pulling out. You’re saying that after going DDS, you just ALWAYS stopped that quickly, to the point you had to beware your location upon stopping? Why?
(1991 Goldwing) 1ST – No I don’t ALWAYS stop fast, +95% of the time I coast to my stops when I can. I take the LEAST congested roads even if it means a little out of my way.
I went DDS is for mileage longevity. The quick stops are a ‘never know when’.
With MT I can lock up both tires, once skidding for about 10 ft. Yup, that was a butt-pucker moment. But with DDS I simply cannot lockup the brakes on dry pavement, there is that much more rubber on the road (as I posted). So with that, yes I do need to look behind me when I see an emergency stop. Saved me several times from rear-enders. Twice now at FULL SPEED, a mini pickup the other a car, neither stopped for traffic red lights. I know, those 2 are not because of DDS but they were a heads up to ALWAYS LOOK BEHIND YOU when stopping. So yes, they sorta go together.
I have had an ’07 Boulevard C90T since ’14 and it had under 25k miles on it. I had a car tire put on at 47k miles and a rear motorcycle tire on the front at about 57k miles. The bike now has over 77k miles and I have been happy with it. I am keeping another C90 for a friend and he has given me the ok to put a car tire on the back of his as well, but I may put another motorcycle tire on it instead this time around since someone else might ride it.
My view is try it if you want, keep it if you want, go back to MC tire if you want, or even stick with MC tire if you want. It is your bike and you should do what you want with it.
skates.fis@gmail.com
what size did u fit
What are your thoughts on going darkside for the front tire of a Harley Freewheeler?
That’s a very good question. We actually had not thought of that. Since you’re really getting no lean angle with the front tire on a trike, that might be doable. Have you put that question to a forum group? We’d be curious to hear some thoughts on that ourselves.
HD’s did it in the 1950s. It didn’t continue long. The extra centrifugal force made it really hard to steer at higher speeds. With a rear MT on front I do feel that stiffer turning. I’ve learned to throw my weight in said direction at the same time as turning. IF you do try it, start out weight throwing a little at first to understand how much your bike can handle. Don’t want to Over Throw it into oncoming traffic or ditch. Believe it, it can be that drastic.
Darkside riding has its time and place. if you want to lean and go fast, don’t put a car tire on it because you will not have the same performance when leaning.
I load up my Goldwing with a lot of tools, I do a lot of highway miles, and I don’t ride aggressively (I look like the dude in the cartoon….). the car tire on the bike is nice if the bike is loaded with a lot of weight, and you can plug a car tire if you get a nail. The bike wants to stay up much easier loaded up and with a car tire at slow speeds and if you go over loose ground, the car tire won’t dig into sugar sand like a motorcycle tire will.
I prefer motorcycle tires if I want to ride casually in the city and enjoy the performance of the bike. but in rural dirt/sandy roads, or long highway trips it’s nicer to have a car tire on the back. that’s just my opinion. Your mileage may vary.