Higher rated axles will not raise the trailer manufactures orig GVWR as the trailers frame strength as designed and manufactured determines the trailers GVWR. The manufacture then determine the size of the GAWRs.
A few RV owners and many equipment trailer owners have upgraded to the next higher rated axles for a better braking system and stronger axle system. However the trailers GVWR stays the same.
Some RV mfg in the past have offered higher rated axles as a option. The trailers GVWR remained the same.
The 571.120 over 10k GVWR and 571.110 under 10k GVWR regs have been posted many times before since 6/15'08 when NHTSA added S10 and S9 paragraphs to the 571.110/120 regs.
The changes were initiated by a NPRM
clicky link from a MRS May, a RV owner, to NHTSA. Its long but a interesting read about the long slow process for rules change and comments from the manufacture reps and players involved in the NPRM.
Old regs had different wording that resulted in a trailer or MH possible overloading the axle/tires.
