Need help with wheels and tires
OK, I'm trying to help my son buy one additional rim and five new tires for his YJ. He has four 15" Cragar "D" window steel wheels on the car. I have no idea what the width and back spacing of his rims are. The current tires are 31x10.5 BF Goodrich All Terrain T/As. He wants to put 32" Goodyear Wrangler MT/R tires on them. The only 32s we can find are 32x11.5s. I have several questions:
1. How do I measure the width and back spacing of his current rims? Is there a diagram on-line anywhere? Do the tires have to be off the rims to properly measure them?
2. Given that he currently has 31 x 10.5s on the car, are we safe to go ahead and buy 32 x 11.5s before measuring the rims? If it turns out that the best way to measure the rims is with the tire off, then we can measure them while we get the old tires removed and the new ones installed.
This is driving me crazy. A model number or something punched into the rim on the backside would have been a really thoughtful gesture on the part of Cragar!