Thanks guys! Dave, they're 3-rail wheels, I have the 2-rail set but being all my other engines are 3-rail running on code 148 2-rail track I decided to keep them 3-rail.
I was thinking exactly what you said, the motorcar didn't pull anything near a long train plus I don't run fast on my layout.
I'll swap them out and see what goes. I have a decibel meter on my Ipad so maybe I can capture the sound level differences before and after.