Are all of your new 315 wheels on the oem Moab rims? Or did you just buy 4 new 315 tires and have the spare the oem? Fwiw... The manufacturer of most 315/70-17 tires recommends a rim size of 8.5 to 10 inches. The oem Moab rim is only 7.5 wide. Can you get away with it? Sure, probably. Would you want to go too terribly far into the sticks aired down to 10-16 psi?
That's quite a bit of play on a small rim.
Originally Posted by smcutter
It's hard to give you good advice at this point. It's almost like you're saying, "I want to have sex, but don't want to get her pregnant. I can't afford condoms, so for now I just want to use Saran Wrap. What brand would you recommend?"