I have seen 31x10.5R15s on a stock 1998 TJ. But they will rub. 30x9.5R15 were the stock "oversized" tires on sports and Sahara's. The Rubicon TJ and LJ came with a STOCK LT245x75R16 and are a true 31" tire and a LT265x75R16 which is a true 32" tire will fit though they Rub (a lot) Rubicons have a slightly different spring rate and length though. One question I have for you, what gearing in in your wrangler? Chrysler had all kinds of optional gear available, what gearing you have will have a lot of "say" in regards to seat of the pants performance opinions.