Hi,
Most 16" rims are limited to only 3,050 pounds, except a few trailer rims at 3,500 pounds.
19.5" rims are typically rated between 3,000 and 6,500 pounds.
22.5" rims are rated between 4,500 and 7,500 pounds.
So the larger rims will carry more weight, and manufactures of tires also make the larger tires carry more weight. Over the road trucks typically will have 24" rims with ratings up to 12,000 pounds per tire.
There are exceptions to these rules, such as the special tires run on low boy trailers, such as ones to carry large equipment to a worksite. They might have 14.5" rims rated at 5,000 pounds each, and then have 4 to 8 tires per axle! Many low boy trailers have 19.5" rims with a 6,500 pound rating.
The larger rims are there to accommodate larger brakes under those rims.
Tiffan might be using 22.5" rims because they get a great deal when buying many at once. And they can use the same 10,000 pound front axles on all their models, along with 20,000 to 24,000 pound rear axles, and this will keep them from having to buy separate sizes for each chassis length. Installing something rated a lot higher than the GVWR will cost the manufacture a little extra, but it is OK and will save them in liability later. The brakes will work better because they are larger than required for the load inside the RV.
Fred.
