When the trailer manufacturer follows the minimum instructions for tire load capacity for RV trailer tires, they MUST comply with the Federal Motor Vehicle Safety Standards (FMVSS).
The standards have not changed. They read – in part – that tires fitted to the RV trailer’s axles MUST provide a load capacity equal to the vehicle certified GAWRs. That rule is unchanged. The rules committees meetings of 2007 & 2010 did not take action on recommendations for an increase in tire load capacity to provide load capacity reserves.
The National Highway Traffic Safety Administration (NHTSA) is responsible for the contents of FMVSS. NHTSA knows and publishes information compiled from actual conditions that 55% of all RV trailers have at least one tire position overloaded. Knowing that, why would they not try to help resolve that overloading with load capacity reserves for Original Equipment (OE) tires?
RV trailer manufacturer’s have the authority to set GAWRs to a lower load capacity than certified by the axle manufacturer. Here is an example of how blatant Keystone got at pushing the minimum standards. Do the math and you’ll see that the certification label is depicting OE tires with ZERO load capacity reserves. I assumed those axles were 5200# Dexter’s de-rated to 5080# GAWR.
Here’s another question about the above information. It’s a known fact that RV Trailer tires degrade. How long do you think it took those OE tires to degrade below what they were carrying?
Most of us that have been writing about RV trailer tires for 10 or more years have always recommended at least 12% - 15% in load capacity reserves are provided from all replacements. Back then there were two brands not being used as OEM, Maxxis & Sailun. When used as replacements with plenty of load capacity reserves their performance was noted as being much better than OE tires. They were proving load capacity reserves that were providing a longer life span for those tires. It’s too bad Maxxis did not start providing more designated sizes and speed ratings.
Finally a huge and powerful RV trailer organization (RVIA) stepped-in and required all of their members – about 98% of all RV trailer manufacturers – to provide at least 10% in load capacity reserves for all OE tire fitments. Because of the way tire industry standards are written for replacement tires, all OE tires being provided on today’s RV trailer axles will be required to provide that 10% load capacity reserve recommendation for all subsequent replacements. The tire industry standard: Replacement tires MUST provide a load capacity equal to or greater than what the OE tires provided. Pun – a catch-22.
I cannot overstress the fact that inflating your tires to the load carried IS NOT a FMVSS standard. It’s a FMVSA standard which is not applicable with FMVSS. Truckers and other commercial carriers do it. Their tires are designed as commercial. They are weighed to the load carried for each load they carry. They stop at weigh/inspection stations and are randomly checked.