Running different size tires on the same axle will cause undo wear on the spider gears, and if you have limited slip, wear that out. So on a rear wheel drive, you don't want different sizes on the back, with front wheel drive, you don't want it on the front, and with 4 wheel drive, you need them all the same size.
The spare tire is supposed to be used for short distances in an emergency only, and you really should have the same overall diameter on the spare as what you run on the other tires.
I got my Jesus on the dashboard, but the Devil's under my hood!
Last edited by Johnbaum13; 01-27-2010 at 05:04 PM.