I got a chance to make 3 more of the flat hub caps.
I did them all the same way as the first - jigsawed out the aluminum, screw to the trim ring, and sand the edge smooth.
Take a look at the construction photo album
HERE.
The hub caps are real easy to pop on and off, so no problems there for checking tire pressure.
Maybe I will make an INSTRUCTABLES about doing the hub caps.
Unfortunately, the hub caps are now the nicest looking thing on the truck! (Bodywork is in the future!)
99LeCouch, got any photos of what you did?