Spare tire size?

[Trigger Creep]

Anyone know where to find a tire size calculator by diameter or revs per mile?

I need an appropriate sized spare to run with my 31x10.5-15's. I need a tall, slim tire that has a 30.8" diameter or runs at 679 revs per mile.

 

[bp71k5]

Why not use a 31x10.5x15?

 

[pauly383]

if your looking for more space in the rear for cargo , find a 215/85r16 ( 30.6 tall , use air pressure lower in taller tire if you have to have perfect match in rear ) and a skinny six lug spare rim ( newer rims require machining axle register hole bigger ) .

 

[Trigger Creep]

if your looking for more space in the rear for cargo , find a 215/85r16 ( newer rims require machining axle register hole bigger ) .

A little more work than I wanted, but the result is better with the thinner rim. 6.8" vs 10.6" section - almost 4" thinner.

Thanks!