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RV Trailer Wheels - Rim Sizes - Load Capacities
According to FMVSS, the wheels provided as Original Equipment on your trailer were approve by the tire manufacturer for such fitments. In fact, every tire manufacturer must provide retailers/OEM providers with a listing of wheel/rim sizes acceptable for fitment for every tire size the manufacturer provides for wholesale/retail sales.
Wheels for RV trailers must have a zero offset.
OE wheel fitments must provide a load capacity equal to or greater than the GAWR axle (s) maximum load capacities listed on the trailer’s certification label.
Wheel PSI limits are determined by the PSI capacity of the valve stem. In other words, a wheel with a 2830# load capacity must have a valve stem rated at 65 PSI or higher. The wheel’s certified load capacity is it’s ultimate load carrying limit.
Tire manufacturers build tires to fit specific wheel/rim sizes. They may build them with an acceptable width range for fitment purposes, such as 5.5” - 7.0“. They will normally determine a measuring size to use for tire specifications when fitted to that size, in this case maybe 6”, then all specifications for the tire will be consistent with the measuring rim size. Sometimes tires are unique in bead construction as in steel cased tires. Such tires may have a single rim width. That width is critical for proper tire fitment to the wheel rim. Some tire manufacturers will list a single rim width on the tire’s sidewall to assist the tire installer in selecting the proper wheel/rim size.
The big problem for RV trailer axles and the wheels & tires fitted to them is overloading. The trailer may scale out at or under GVWR but the axles may have an overweight problem. The problem is normally from a severely unbalanced condition that causes the axles to be carrying a combined load within their capacity but not evenly. One end may be 300#-400# heavier than the other end. The tire and wheel in that overloaded condition have a higher probability factor for failure.
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