Good question! The following table explains what fits. Note that Jeep Wrangler YJ and TJ are different. Also, tires sizes between manufacturers are not the same size. Some tires have a thicker lug and are thus a little taller than the indicated size and vice versa.
Don't forget that tire WIDTH also matters. The tires might fit under your rig but may rub when you turn. You might also need to modify the width of your fender flares if your tires extend past the ones you have on there now. Some states require that your tires be covered completely by fender wells or flares to prevent debris from flying.
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