4 door 31x10.5x15

OK I hope some can help me out here. I have a stock 2001 Jimmy 4 door. I would preferr to not put a lift. I have run 235/75/15 MS, but would like to run 31x10.5x15. I have come accross some people saying you need a lift, others say no just crank the T-bar inch and put 2 inch shackles. Well I...