I got two coats on the LGB wheels and they look pretty good. I probably should have used some primer or white first to cover the black but oh well.
The signal red is a pretty close match to the wheels on the loco. However, and I never really noticed it until I went to paint them, the wheels on the tender of the 21181 are a different color. The loco wheels are an orangish red. The tender's wheels are more of a pinkish red. So, now I have tender wheels which match my loco, have less drag, and two extra power pickups. <yay> I found that just from swapping out the brushes for ball bearing wheels in my other Mogul allowed that engine to pull one extra coach or two empty freight cars up my 3% grade.
I put the old red wheels on one of my Christmas cars. I might paint all my christmas car wheels a bright red as they look good.