Hi I'm new to bikes and I've never heard of putting car tyres on bikes. Sorry for being ignorant but can some one tell me why you do it, what are the advantages? I like your no mouthing off rule but it means I can't find a thread where you say why you do it

 

The reason I switched on my previous bike, a GL1800, is mostly out of curiousity. The guys that ran them LOVED them, and the guys that have never put miles on a car tire hated them. I was extremely sceptical at first, as I had the same thoughts. A car tire does not have a round profile, so how can it possibly corner!? I rode behind a guy with a Michelin Alpine RF on his GL1800, and watched the tire intently. I was completely shocked when I noticed that with normal cornering (such as slight bends in the road that do not require big lean angles), the flat surface of the tire barely left the surface. It was at that moment that I realized the extreme amount of grip that could be attained with the car tire.

I followed him on a twisty road, with peg grinding corners, and was further shocked to see that the car tire had at least half of the flat surface of the tire on the road, and the rest of the tire would just bend and flex. This only peaked my curiousity more.

I then watched a few videos of a guy named "yellow wolf" on youtube running the "Tail of the Dragon" on a Yokohama car tire. If you're not familiar with his name, he lives on or near the dragon, and knows it like the back of his hand. He was able to ride at the same insane speed or faster on that road with the car tire as he was with the motorcycle tire. Believe me when I say that he pushes the performance and handling curve of the Honda GL1800 to its limits. So I thought, if Yellow Wolf can abuse a car tire and not burst into a ball of flames, then surely I would be safe.

Then there is the milage you can get out of a car tire. I was burning through motorcycle tires every 5 thounsand or so miles on the GL1800, becuase of my heavy right hand. I have heard of guys getting 20,000+ miles from the car tire, that are less expensive, and have a run flat feature.

So I bought a Michelin Alpine RF. I was nervous at first. My first corner I think my heart was in my throat becuase it felt... wierd. I had to push a little harder on the bars to get the bike to turn. I'm not that big of a wuss, so I dealt with it, and rode on. About 20 miles down the road, I was getting convinced that the car tire was not going to spontaneously burst into flames. As I pushed the bike harder and harder in the corners, I realized that I was riding faster than I did with the mt on the back. After about an hour of riding, I felt completely comfortable with the car tire, and swore to never go back to a motorcycle tire. After a few months, I was so comfortable that I had to replace my pegs becuase of grinding then in curves, and slow speed maneauvers in parking lots.

One day, I needed to perform an emergency stop because I was in my own world, and was following too closely when traffic got heavy. Totally my fault for needing to use the techniques I practice in empty parking lot, but boy did it pay off. I grabbed a handful of front brake, and judiciously applied the rear brake. I was pushing the rear brake about as hard as I could, and the rear tire did not lock up. With the combo of the front and rear brake, I was able to haul that thing down to a safe stop, and not slam into the guy infront of me.

Additionally, with the car tire on the back, it aided in slow speed riding becuase it took less effort and rider input to keep the bike balanced under 10 mph.

That said, buy a used rim, mount a car tire on it, and take it for a few hundred mile spin. You will not need that manny miles to know if it's for you, but miles = smiles! If it's not for you, then you can sell the combo and only be out a few dollars. If it is for you, then you have a great tire and smoother ride for the next 20,000+ miles.

My Ultra Limited only has about 1200 miles on it, and I bought it a little over 3 weeks ago. My next rear tire will be a Michelin Alpine RF. When I traided my GL1800, the ct had about 8000-9000 miles on it, and it still looked new. No cracking on the sidewall, no seperation (at least not that I could see) and no problems.

The only issue is uneven road surfaces. The bike would track a little on uneven roads surfaces, or grooved pavement. As long as you're not asleep, you will be fine. If you're watching the road like you're supposed to, you will see the surface change, and be able to anticipate the tracking, or change lane positions and avoid it all together. I'm definately going back to a ct as soon as the stock tire is toast.

 

Cool, that explains a lot thanks
It makes sense that you would have better grip seeing as you have a bigger contact patch. I wouldn't be surprised if you can get better water dispursion too with the deeper tread.
Thinking about it, I have a lot of experiance with older cars and some of them (the saloons etc.) lean a hell of a lot, my Amazon in standard form leaned over so far when pushed, petrol would spill out the filler neck and that combined with the positive camber it got in the corners would leave you using the sidewall. Never once did it fail to grip though.

When you use the car tyres do you end up on the sidewalls? I imagine not as a bike is so much lighter?

 

Nope, it never touches the sidewalls. The sidewalls just deform or crush down, only slightly. I'm sure at really high speeds (think Isle of Man TT) physics would start to be a problem, causing the sidewall to pench against the rim, but I know for a fact that my Ulta Limited will not be cornering at speeds more than about 90mph anyway. That being the extreme top end. If you watch the slow motion Isle of Man TT vids from the guys jumping over the hill at Crosby, you'll see their tires go under a tremendous amount of flex, and the sidewalls crush down signifigantly. I've never seen evidence to lead me to believe the sidewalls on our bikes are under that much stress to cause them to fail unexpectedly.

I did push my GL1800 through turns over 100mph, and it felt sold. The turns were not too sharp, and I was about two or so inches from peg grinding. But they're totally different bikes. Goldwing is basically an obese sport bike, and my Limited is a cruiser. I'm done with the 100mph stuff, but I know eventually I'll push my Limited to it's limits.

If you've ever seen an under-inflated tire on a car or truck, you'll notice the sidewall will discolor from heat, mostlikely due to the sidewall being under a constant state of flex. I had my CT inflated to about 32psi cold, which would warm up to about 37psi. I monitiored the color of the sidewall everytime I washed the bike, and never saw any discoloration. I really never saw much wear on the most outside part of the tread. The middle seems to wear the fastest, unless you air down to about 27psi, which lets it wear more evenly. The more air pressure, the more rounded the profile, which makes it a little easier in the twisties (less bar input, easier flip from one side to the other). I found that 32psi cold was the sweet spot for me, but I do have a heavy hand.

Check out Yellow Wolf's videos on Youtube. I know he has a darkside vid on there.

 

Looks like he's got a CT on his bike in this vid, but it's hard to tell.

 

Cool vid. It does look far too square I'm guessing CT too. And I guess the forces are very different when a car leans, it's pulling on the tyre rather than pushing on it.
I think I'd like to try this... Need to get my licence and some confidence in riding first then I'll give it a go
We dont really get discoloured tyres here in the UK, I guess it's too cold, you generally know it's under inflated cause theres no edges left on the tread

Whats the big taboo with this? I can see nothing unsafe about it. At the end of the day a CT is designed to cope with more weight than that of a bike. That said what car wears tyres that skinny on such big wheels?

 

Here is a link to a review I did when I went over to the dark side. I currently have about 8 or 9 thousand miles on that tire and it still looks new. I can see no reason (other than buying a new bike) why I would ever go back to a motorcycle tire.

https://www.hdforums.com/forum/the-d...ng-review.html

Why is it taboo? I guess because some folks are scared of new or different things. I can't tell you how many people who never actually tried it told me it would not work. People actually asked me if I was trying to make my kids orphans....

 

Interesting read, thanks. I will definitly be looking in to this when the time comes