RE: Calico 4/30/05 - 5/1/05
Look for the actual tire size, it should be something like 225x75R15 or something like that. That size would be around 28".
If you have stock wheels, and they are the 6" variety, you will want to go no bigger then 235x75x15 tires (29"). any bigger and the tires will rub the leaf springs when turning. (these skinny wheels are really too narrow for anything else anyhow)
6" wheels look like these:
If they are the 7" wheels then you are okay up to a 30x9.50x15 (30" tire). 31's will rub the wheel wells when offroad. Every other stock Jeep steel or alloy wheel was a 15X7 in 1990, unless they offered a 15x8, but that would definately be alloy.
A small lift of any kind and you'll be able to fit 31's.
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If you have the 6" wheels pictured above, I'd wait until you can afford some wider wheels. Try Quadratec for their Cragar "Soft 8" wheels, the 15x7 and 15x8's are really inexpensive
I have a set on my Cherokee.