Are stock 16"x5" rims different on '71 & up disc brake trucks?

[wilbilt]

Originally Posted by Clanky

Thanks you guys for your responses, I know way more now what to look for. Wilbilt, on the wheel photo, I see 4 nubs for the hub cap, but I swear I've seen wheels with only 3, do you know if there were both or is there is some significance there year or plant wise?

I don't recall ever seeing any with 3 nubs, although I suppose they probably exist. Wheels were sourced from various vendors (Kelsey-Hayes, Firestone, etc.) as well as GM production. As SS Tim posted, there will be a code stamped on the wheel designating the size and rim contour that you may be able to match up in factory data. The one in the photo is a 15 x 6 JJ, which is typical for a welded wheel designed for tubeless use.

Many tube-type wheels have centers that are riveted in place (not airtight) and lack the circumferential ridge on each side near the bead seat that helps maintain bead pressure to hold air. It also seems like tubeless wheel are thicker (heavier), or maybe I am just getting older.