I have a 53 1/2 ton. Original tires were 6.00x16. You could mount 6.50x16 on the rear for added load capacity. I rebuilt my truck a few years ago and changed to new wheels and radials. After new kingpins, other front end work, new shocks and a good tight steering box, I still kept experiencing the front end jumping around on uneven pavement, like where the two lanes of asphalt meet and form a seam at the centerline. The reason was those old bias belt tires. I did a lot of research and got a lot of advice, some from this list. Some said you can run radials on the original rims (which if I recall are around 5 1/2 inches wide). Others said that was too narrow for radials and was unsafe. Still others said radials on the original rims were OK, but I'd need tubes because the old rims might not seal. I elected to get new wheels. 15x7 smooth wheels from Obsolete Chevrolet. They get them from California and I'm sure there are many vendors...You just have to make sure you get the right offset so the tires or wheels don't rub. I married the wheels with 215/75 radials. The reason I used these sizes was because at that time, I found few reasonably priced 16" whitewall radials, and the new combination seems to come closest to the original wheels/tires' circumference, so the speedometer is accurate. I sent my original hubcaps along to Obsolete and the California outfit modified them to fit the new wheels, which have bumps instead of clips like the originals. Well, long story. I like the look...it's very close to original, but the ride and handling are so improved, it's hard to believe. Here are some pix of the truck with shots of the wheels.
http://albums.photo.epson.com/j/AlbumIndex?u=1784934&a=13816194&f=0
