Hi everyone,

I've another question that isn't specific to z-car science, but is relevant to the general setup thereof.

My question is in regard to stretching a tire across a wheel for which it's too narrow. A 205 tire on an 8 inch-wide wheel, for example. It seems that, in many cases, this is done simply becuz the owner likes the look. In other cases, it seems it's done because the proper-width tire doesn't fit under the fender. My question is, what does this do to a tire in terms of its structural integrity and performance? Is there a threshold where a tire can still perform safely under aggressive driving conditions (autocross or a track day, for example)? At what point does the trade between making it fit and pushing the mechanically safe limits of the tire become dangerous?

And, to specify a bit, I'm referring specifically to road-legal tires. I understand that specialty race tires are often built with different types of sidewall (cantilever type comes to mind).

Thanks, everyone!

There are generally no structural integrity issues with the tire when stretched. The big issue is popping a bead under lateral load or from pot holes. The tire pressures you'll have to run to prevent bead popping will significantly reduce grip. To get the best performance out of a performance tire it should be mounted on a rim that is equal to to or 1/2" wider then the actual tread width measured from tip to tip of the wear triangles.