The Stovebolt Site Forums The Shop Area General Truck Talk 6 lug rim identification??

Howdy all!

I'm currently rounding up stock rims for my 59 Suburban. I have been given and purchased numerous rims. 15 in. They seem to come in two different styles. On the front side of the rim some of them have a smooth singular bulbous look. Others have a double rim "ridge" on the front. They are all configured with 3 clips ea for period hubcaps. Overall outside diameter is 16.5 in and total width is 6.5 in.
What would be the difference?

Thanks!