When I purchased our present rig, I was not too happy with the CCC. SO...I started digging to find out the basis of the figures.
After MUCH discussion with Spartan (chassis) and Rexhall (coach) plus calls to the makers of the axles and brakes to get their numbers, it turns out the actual basis of the ccc was the el-cheapo load rated 'G' tires ordered for the chassis!! The chassis, the axles, the brakes and other components had higher allowable capacity!! THEREFOR...with an upgrade to 'H' rated tires, I increased the true ccc greatly!!
FWIW - the fronts were OK weightwise, but the rears were the problem - In my case, the Goodyear 22.5 'G' rating is 5780 in dual configuration, 'H' is 6750 lbs. So the four replaced tires improved my rated capacity by 3880 lbs - but the tires are now more than the axle rating, so I now use the axle rating as my maximum - and stay well under it!!
PLEASE - this is my specific situation - do your own research about your own rig and make an informed decision!!