I did it. Switched over to the car tire today. I had a lot of trouble getting the tire to seat completely on the wheel. It would seat about 300 degrees but that last little bit just didn't want to pop out all the way. I tried several times in my shop and then took it down the road to a mechanic friend that does mainly front end alignment and tire replacement work. He got the same results and wasn't willing to put more than about 80 lbs of pressure on the tire. Next I went to a Suzuki dealer that's right behind my friends shop, they spent about 45 minutes on it and got the same results. Surprisingly, they never even mentioned that I was putting a car tire on a bike, I kinda expected to get some flak from them, but they seemed to think it was fairly common, and had no objections to trying, but they wouldn't put more than 55lbs of pressure on it. So I went back to my shop and tried a few more times, but no success. Next I called a commercial tire installation company and explained my situation, the owner told me to bring it on down and he'd get it on. I took it in and his first words after seeing the tire were, "well, there's your problem, your trying to put a car tire on a motorcycle rim." Yes, I replied, I'm tired of replacing the rear tire every six months. He told me that he rode a bike too, and he took my tire back to the shop area. I looked through the shop window and watched as he hooked it up to an air hose with a clip on it and then got about 6 feet away and put the air to it. In a few seconds I heard a loud "pop" then a few seconds later I heard another "pop". He then instructed one of his guys to let some air out of the tire and then brought it back to me fully seated. I asked him what he did to get it to seat and he said, "I put 110 lbs of pressure on it". Wow!
I was pleased when I got home to find that the 155 width tire, mounted on my rim, was exactly the same width as the 145 motorcycle tire mounted on the rim. I put calipers on both tires and they were exactly the same width, about 5 5/8".
Here is a shot of the calipers on the new BFGoodrich 155/80 R15 tire.
The next picture is the calipers on my Michelin 145/90 15 motorcycle tire and I didn't move the calipers at all after measuring the BFG tire, and you can see that they are both touching at the widest point.
Here is a shot looking down on the two tires side by side. You can see a big difference in the profile of the tread, and the motorcycle tire appears to be larger in diameter, but for all practical purposes, they are close enough.
Once I got the new tire balanced, which was a lot easier than balancing the motorcycle tire, and took a lot less weight to make it balance, I installed it on the bike and took it for a spin. I am using 35lbs of air in the tire. I don't really know how to determine the proper amount of pressure, so I'll just have to play with it a little and see how the tire is wearing.
I started out running some neighborhood roads and then took it up on state highway 27. Got it up to about 70 mph for about 3 miles and then turned around and came back the other way. Next I ran a local twisty road to see how it handled in the curves and then I took it up on Missionary Ridge and ran some more curves. Dropped down to East Ridge, Tn and headed out to I-24, took it back up to about 70-75 then headed south on I-75 for a few miles. Got off the highway, took some more twisties and came home.
Here's my impression. It does feel different than the motorcycle tire. Not worse, just different. I found it to run smoother and with less vibration than the motorcycle tire. It is easier to maintain your direction when going straight ahead, and you can almost balance out and not put your feet down at a stop, which is kinda cool. I also found that it corners great, just as well as the MC tire, maybe even better, but definitely not any less. It does take more "effort" to lean into the turns, but it's also easier to pop back up when you come out and switchbacks are not a problem at all. I never scraped the pegs but I was fairly aggressive in running the s-turns I hit tonight. I also took a few minutes and drove around in a gravel parking lot to see how it would do. Not a lot of difference there, but the back end never felt like it was sliding out at all, so maybe a little improvement over the mc tire.
Well, I'm not saying anybody else should do this, and I'm not saying it is a good idea or recommending it, but I will say that I'm glad I tried it, and I think I will probably stay with it. I like the way it feels, and I'm hoping it will last 2-3 times as many miles as my MC tires were. My friend who owns the alignment shop also rides and he said he had three people he knew who rode CT on the back tire of their Motorcycles.