[Formula43 Wheel]

The best way to get the specs. is to look them up on Tire Rack or the tire manufactures website. General rule of thumb is to match the tread width to the wheel width for optimum performance.

The BFG Rival 335/30-18 is as follows:

http://www.tirerack.com/tires/tires....=yes&tab=Specs

Tread Width = 12.7"

Section Width (overall width) = 13.5"

I would recommend the Rival 335 on either a 12.5" or 13.0" wheel.

Here's what I use determine tire clearance.

13.50" (section width)
-12.75" (overall wheel width, add 0.75" to the advertised wheel width)
_________
= 0.75/2 = 0.375" of tire overhang on each side.

I would allow at least 0.25" of lateral movement of the sidewall from side to side.

0.375 + 0.25 = 0.625

You'll need at least 0.625" of clearance on each side of the wheel and this will still be tight. Also consider up and down movement and the big radius the inner fender wells have.

I hope this wacky formula helps!