How big of tires can i put on a stock 1993 Chevy Silverado z71?

-how tall and wide of tires can i go with little or no cutting of the fenders and without cranking the torsion bar all the way. the tires will either be on 16inch rims or 18inch rims.probably like 38's if your really luck
The best site I use is discountTire.com