My first tire suggestion...........
BF Goodrich!! Any of the "terrain T/A" series......(assuming you can get 'em in 18" or whatever size you choose).
As for wheels............well...........I'm not familiar w/ Chevy lug patterns, but assuming the newer stuff fits your '94, you might contact local dealers asking if they've got any "pulloffs" from people who upgraded their wheels right off the lot. (Obviously, this is if you like any of the newer Chevy wheels).
Assuming you're not lowered, I kinda' like this look (minus the side effects).........
http://images.hotrod.com/incom...grade+side_profile.jpg
Now......if you wanted to lift it..........then we're talkin' a whole new ballgame........
http://www.jacked-up-truck.com...ed-chevy-truck-001.jpg