Joe,
If this is for your M37A3 project, I would advise you against the rims. I thought they were neater than sliced bread until I started messing with them during my M101 repaint. I had a pair of both versions and both style of run flat inserts. They don't inter mingle and they are a pain to seal up. I think 3 different o-rings were used over time and you have to have the correct ones for your rims. Actually, you need new correct ones to make them hold air. I just slobbered a bunch of wheel bearing grease on my used o-rings and it worked.
I know they look cool, but a set of painted 1 piece tube less rims will be a lot less hassle. Cheaper too.