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Car tire on 650 V Star?

I have a 650 V Star Custom with a Velorex 562. I am interested in replacing the rear tire with an automotive tire and wondering if anyone has fitted an automotive tire on the 650 V Star? If so, what brand of tire and what size was used. Also, where can you have an automotive tire mounted on a motorcycle rim? I assume a normal automotive tire shop will not have the right equipment for a cycle rim? Will a motorcycle shop be willing to mount an auto tire? My cycle has an after market "bobbed" rear fender and I believe there to be more room than the stock fender and am not anticipating a clearance problem. Any advice will be appreciated.

This is not as easy of a question as one might think to answer. One of our demo bikes is also a 650 Vstar for which of course we make bike specific mounts for as well as triple tree's to lower the steering effort so I took a look at it to find out the tire size. Your rear tire is a 170 80 15. This means that it is about 170mm wide, 80% as tall as it is wide and 15 inch diameter. Motorcycle tires are always width wise rounded to the nearest 0 while automotive tires are always rouned to the nearest 5 so the automotive equivelant would be a 165 80 15. This size is no problem at all to get as it is the size VW ran for years on the Beetle. The problem is in the diameter, where one would think that 15 inches is 15 inches this is not the case. Motorcycle rims are about 15 1/4 inches in diameter while automotive rims are a bit under 15 inches. So an automotive tire end up being about 1/3 of an inch to small in diameter for your rim. Many people have mounted an automotive tire onto a 15 inch motorcycle rim, others have found it hard at best to get the bead to seat and still others have either gotten hurt trying to do this and or destroid the wheel in the effort. The proper way to do this as your wheel is most likley a wire spoke wheel is to change the rim to an automotive size, Again this is not as easy as it could be. In the 15 inch size motorcycles usualy either have 36 or 40 spokes while cars have 48, 60, or 72 spokes. If the angle are correct with out custom drilling a blank rim it is possible to run an automotive 72 spoke rim on a motorcycle 36 spoke hub by using 1/2 the holes, not really the best idea. If your rim is cast it may have enough material to be able to be turned down on a lathe. Most people end up just working on getting the stock rim to work, Again not really a good idea. As you have noted most tire shops will not help you so you end up having to mount it your self. We for some bikes (mainly BMW's) make custom wheels but we do so with an automotive wheel and an adapter for the bike this way you take the wheel to an automotive tire shop and as long as you do not tell them it is going on a motorcycle they have no issue mounting a tire to it.
While this does not apply to your bike as people will be reading answers to this post for many years to come in the non 15 inch diameter motorcycle rims and automotive rims are so close in size as not to matter, the problem you get into is finding an automotive tire that is narrow enough to fit the bike.
Jay G
DMC sidecars

Jay G DMC sidecars 15616 Carbonado South Prairie RD Buckley WA 98321 866-638-1793 Hours Monday - Thursday 6-4:30

Jay, thanks for the comprehensive reply. I am in fact using your V Star specific mounts, and find them to be an extremely efficient and structurally sound way to mount the Velorex with the V Star. I would recommend these mounts to anyone considering this combination. I have owned 5 different sidecar rigs and have followed the "darkside" pro and con arguments for years. I am not willing to attempt mounting the tire myself because I simply don't have the proper equipment. Therefore, my attempt to pursue the mounting of the auto tire will most likely boil down to whether or not I can find a local motorcycle shop to mount the tire. I am not willing to modify the cycle wheel in the manner you suggest since I feel it would most likely be cost prohibitive, erasing any of the savings I would gain from using the cheaper and longer wearing auto tire. I guess I will make the rounds to the local shops and see if anyone is willing to take on the challenge of attempting the mounting process. Thanks again for the reply.

Attached files

Bear in mind that the 15" automotive tire could fail at anytime later even if it got mounted and seated without failure at the time. The integrity and strength of the steel bead and the rim area casing have been seriously compromised.

Ever had a high speed rear tire blowout that came out well?


shoelu, please take a look here for a prior discussion with pic re: 15" car tires:

Lee / Summer Grove, Louisiana: Ural cT, CJ750, Burgman/Texas Ranger, Zuma 50F, MB5, TW200, CRF250L, GTV300

Well, I have to admit that I never realized that the 15" wheel had specific problems and difficulties that are not necessarily associated with other wheel sizes. After more research and weighing the advice offered here, it seems that the savings is not worth the risk in this case. I guess a traditional tire is most likely in my future.

Lonnie asks:
Ever had a high speed rear tire blowout that came out well?

Not a rig, but on a solo Honda CB650:
It wasn't high speed only something like 40-50mph but actually on 24.12.83 around shop closing time at over takeing a car a stone cut into the back tire....
Lukily the guy didn't hit me and I could roll out. What I do remember well is pushing for 2km to the gas station and no present for my forster sister...
By the way it was the poorest chrismas we ever had. The forster father had left the family for to continue to live with his "princess". and I was a soldier on the fabulous wage for national service of 240mark (145$) a month...Before as college scholar I had earned 3-4 times in my free time.
Such is life.

I was unsuccessful in trying to get a car tire onto an 1100 Vstar some years ago. Nothing I did could get it to set the bead. This may be a Yamaha thing as a couple of years leter I successfully got a michlyn auto tire onto a 15 inch Suzuki rim. In fact over the next few years, I did 3 Suzuki wheels this way, always with michlyn tires.
One was for a friend who had exploded an auto tire trying to set the bead. These were all for wheels for S-40 Suzukis.
I am of the opinion, based on my own experience, that some brands of tire will stretch more than others, and that different motorcycle rims from different bikes may have slightly different dimensions where the bead has to set.
The Yamaha 1100 Vstar had a very promenent ridge that the bead had to stretch over before it could set.
This ridge is probably to help retain the bead should tire pressure get low. However it is a complete problem to beading a dark side tire. I believe that motorcycle tires are made of softer rubber than auto tires to help them stick to pavement better when cornering. This is probably the reason that a motercycle tire does not last as many miles as a car tire.
This and the slight diameter difference is enough to make it impossible to mount some tires.
My S-40 with sidecar got more than 20 thousand miles to a tire with the darkside Michlyn tire. The original rear tire was wasted in less than 4 thousand miles. For a front tire I mounted an Avon sidecar special which got more than 25 thousand miles n sidecar usage. They are only available in 19 inch. An 18 inch sidecar tire is available from Metzler
That works very well