Roy -
I've got the Dueler ATs (31") on my 91 with about 30k mile on them already. They are decent tires, ok in the mud and snow. If you want to go with an All Terrain tire, I'd not recommend them, go with the Pirelli Scorpion ATs, they were tested and beat out the Bridgestone Dueler ATs, BFGoodrich ATs, and Good Year Wrangler ATs for ride comfort, wet/dry traction, low noise, and the best thing is, the Scorpions are the cheapest. If you were to go with MT tires then Bridgestone just came out with the new Dueler MTs, superior to BFGoodrich MTs but not as good as the Good Year Wrangler MTs.
Good Luck shopping.
Khoa Vo
(semi-modified '91 Explorer)