Is it a 2X4 or a 4X4. If it is a 4X4 you should be able to put 31/10.5/15 on with minimal rubbing on the frame at full turn, this would be with factory rims or aftermarket with equal backspacing(5.5" I believe). Check this link http://s10-4x4.com/HitFit/ it will help. Hope that helps.
1995 S10 Truck, 4X4, Ext. Cab, 4.3 Vortec V6, 31/10.5/15 BFG TA's, 3" Trailmaster Body Lift, Westin Side Bars.
Ryan Sharpe Denver, CO.