I have a tag axle on my M.H. and I would be more concerned with the breaks on it then how the wheels looked.
The tag axle on my M.H. has a master cylinder all by it self and you should make sure that when you have some one check your break fluid ask them if they had check the reservoir for the tag axle.(not all repair people are aware of another reservoir.)
It's located in back of the dulls wheels up under neath the back of the motor home on a Chevy 36' 1997 Dolphin M.H. it cost me $2,500.00 to repair mine.
Just a thought.