Originally Posted by
IdahoMtnSpyder
I thought I had read in the Federal Regulations that a tire had to be labeled as to its intended use, but I can't find that specific requirement now. It might be in some official guidance or interpretation document related to the Federal regs. I'm pretty sure most tires ARE marked for their intended use, P for passenger car, LT for light truck, M/C for motorcycle, ST for special trailer, plus others. I just found a pic of a Kenda Ryker tire and it has M/C after the tire size designation. I'm sure Kenda adds the special motorcycle label to clearly show it is not a normal m/c tire even though it is in the general class of m/c tires. I'd have to look but I think the testing requirements for m/c tires are less strict than for car tires. What I have found in the Federal Regs is a requirement that the tire manufacturer must make known through publicly available documents (that does not mean free) of all the rims a particular tire has their approval to be mounted on. That document can simply make reference to specific rim styles in a reference document from any one of several tire and rim manufacturers associations. I'm sure we could find where Kenda says mounting their Spyder tires on a Spyder J rim is an approved installation, but approval may not be shown for usual car J rims. Maybe they do say that which is why the special motorcycle label. In other words Kenda's official position may essentially be that the Spyder tire can be used on any proper size J rim as long as that rim is on a motorcycle. But, and this is a big but, if Cooper or General or Vredestein, or whoever, does not say their tires are OK to mount on a Spyder rim, which probably is identified by more characteristics than just the J rim design, or that it is OK to mount their tires on any J rim including ones used on motorcycles, then a tire dealer is within his rights to refuse to mount such tires on a Spyder rim. What we need to get is the tire makers to say it's OK by them to mount a specific car tire on a Spyder rim. Or better yet, get the tire and rim manufacturers to grant blanket approvals for certain groups of tire designs to be mounted on certain groups of rim designs.
It's really a case of splitting hairs where in the absence of a clear OK designation, the assumption is it is not OK. In our case we have plenty of experience to show that using car tires on our Spyders is NOT "not OK", but unfortunately the folks who are in the position to declare car tire use is OK don't seem to want to do that. As to legal/illegal it's a bit nebulous in my mind. Mounting a tire on a rim that is not listed as being an approved rim for that tire is contrary to the Federal Regs, or at least its intent. But I would say it is illegal only if the law states that mounting a tire in contradiction to the regulation is prohibited. If that is the case then mounting a car tire on a normal m/c rim would be illegal, but then so would be mounting a car tire on a Spyder rim if the Spyder rim is not listed by the tire maker as an OK rim to use. With the vast variety of tires and rims out in the world, and millions of combinations that are possible, it's probably nigh impossible to come up with clear regulations and exceptions to cover every situation.
My position is use a car tire if you want, but don't get all bent out of shape at a Can Am dealer who won't mount it for you. There are plenty of other tire technicians out there who will do it.