8x6.5" (8x165 MM). Wheel Side Bolt Pattern: 8x6.5" (8X165mm). PUT 8 LUG NEWER RAM 2500 WHEELS ON RAM 1500. 5x5.5" (5x139.7 MM). Vehicle Side Bolt Pattern: 5x5.5" (5x139.7mm). You need two sets of lug nuts for these adapters to work.
I do not recommend these adapters. You will have to spend about $75 for "low profile" lug nuts before you can use the adapters. The low profile lug nuts are hard to find (I had to have NAPA special order mine) and not as strong as full size lug nuts. A slight change in the design of this item would alleviate this problem.
Took a set of 8 lug rims with 35 inch tires and adapted them to my 1999 Ram 1500 that I’m building. Yes I had to buy standard lug nuts 5 a wheel in my case. They pretty chrome ones are not stronger as a previous reviewer indicated. They are same number of threads just with a pretty chrome cap on them. Cost me $45 bucks to buy 20 standard and do it right. Still a good deal.