spare tire size

[jpyoung]

I was having a discussion with a fellow car guy awhile back and we got on the subject of space saver spare tires etc.  The question neither of us knew the answer to involved the height of your spare tire. Basically, could driving your car with a spare that is not the same height as your other tires cause a problem with the rear end?  Especially if you are running a posi-trac type rear end.  Thanks in advance.

[Horseplay]

In a word no. It's not going to hurt things mechanically, as a general rule. Clearance issues and such may be a concern. If you are running tires that have very close tolerance to rubbing or such, a smaller tire may cause things to sit such that you might get issue somewhere. You also need to make sure you have room for disk brake set-ups.

[jpyoung]

Thanks, we were wondering about one tire turning different rpms than the other and the affect on the third member.  Does that make sense?

[AzPete]

It would be the same as turning a corner forever. The rear tire turn at different rates much of the time. No problem. They do recommend that you not run different sizes for an extended time....you know, get the flat fixed and back on the car.

[jpyoung]

Makes sense now, never thought about the turning effect.

[AzPete]

When one thinks about that, there is actually very little time that both rear wheels turn the exact speed. Air pressure, tread wear, brand, tire temp, and the drivers ability to hold the car perfectly straight all work the differential. The road conditions also come into play.

[Horseplay]

Don't forget all the time most of us guys spend up on two wheels doin' the whole "Dukes" thing! :craz