The size tires you're looking for would probably be an LT215/85R-16; they work well to replace the 6.00 to 7.00-16's. As was stated before,it's not a problem to run radials on the old original wheels,with some concerns; Often older wheels will have loose rivets holding the rim to the web. That makes them leak,so tubes must be used,or the rivets must be tightened or the webs welded to the rims by a qualified welder. also,the newer wheels have a safety bead,which serves to help keep the tire bead from seperating in the event of a blowout or a side impact on a low tire,such as clipping a curb,etc. This is usually the reason tire shops soetimes are reluctant to fit new radials to old wheels. Also be sure there's no rust at the point where the rim and web connect-this will weaken the metal to a point where the wheel may seperate under a relatively minor impact. As long as your wheels are in good condition and don't leak air around the rivets,you'll be fine with radials.
And actually,radials have more sidewall flex than bias tires;that's what enables the tread to stay flat on the pavement during hard cornering. So if you're going to be driving like Darrell Waltrip,it might be best to buy some more modern wheels.
I've always swapped the bias ply tires out for radials on my trucks,and never had a wheel-related problem. But that's just MY experience.
Speed
