If price is a big concern and you want offroad tires that look tough, consider Hi-Tec Retreads... I know you're thinking "retreads? bah!" but they have lasted really well for me, and they are a bargain.

http://www.high-tec-retreading.com/sizes.html

I opted for the green diamond tires...kinda cool... I have done some little tests of my own with wet pavement and it's really hard for me to get these tires to spin! With my old tires (also from this website but without green diamond) it wasn't hard on wet pavement to spin them.

Also, if you care much about the environment, this might interest you: It takes 22 gallons of oil to make a new tire but only 7 gallons to retread an old casing. Imagine the petroleum savings if everyone used retreaded tires... I know that's not gonna happen but it's something to think about. And most new tires, once the tread wears out, can be retreaded at least 2 times.