Wheel Sets that using Machined SideWall Brake.
a) Check/Adjust brake for tension.
b) Check/Adjust if worn Replace new brake pads.
c) Check rims walls for any worn out sign.
Rims brake are machined sidewalls.
Normally there is a machined grooves on the side walls for
optimum for water dissipation & brake contact if can remove the
compounds that sticked on the groove.
Constant braking on rimed walls shall generates heat thus would
be cracking the walls if sided wall rims are worn.
Just mine 2 cents.
Cheers,