ok im shopping for new tires, i curretly have toyo m/t's 35 x12.50 20's (please can we get past the 20's) im thinking of moving up to 37's? how will i know if i have the clearence? i have a 4' skyjacker lift if that helps. also whats some mud tires out there that are good? im thinking the nitto mud grapplers? any others?