Are they 31's or "about" 31's? If they're 31's, they shouldn't rub unless the front suspension has sagged A LOT. Given that it's an '01, I wouldn't think the coils could've sagged enough to cause rubbing, but who knows. More than likely the alignment needs to be adjusted forward. Are they stock rims and tires, or aftermarket? If the rims are aftermarket, they may be too wide, or of improper backspacing. If the tires are 31's, are they 31x10.5's or 31x12.5's? Wider would rub easier.
You've checked to make sure the frame isn't bent?