An overly hard tire will bounce, Remember that we have no "shocks" per se to smooth out the road shocks. Once they start bouncing they will start to wear funny (well not so funny). Cupping is a sign of bad shocks in an automobile.
I still question how a C rated tire would up on that camper with 4 other Ds (3 on axles and 1 on the spare carrier).
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW