By Roger Marble
“65 psi is too much” was the opinion posted on an RV Tips Facebook page by Tom. He said: “OK, I can’t find any info here so one last time. The tire pressure says 65 psi cold on the sidewall of the tires on my travel trailer. That sounds like a lot to me. What tire pressure do you run your camper at?”
I’m not sure where he did his search. On the FB page, he did get some answers such as “60” and “110” and “80”.
As an actual Tire Design Engineer, with 40 years of experience including decades of trailer ownership, I can explain why you need to follow the Science of proper tire loading and inflation.
You have a Certification sticker or label on your travel trailer that was applied by the RV company based on safety regulations. The sticker tells you the correct information for tire size, type, and Load Range. It also tells you the GAWR (Gross Axle Weight Rating). You should not exceed the GAWR because you can break wheels, bolts, axles, hubs, springs, and related parts. Known strength limits of these parts were used to establish the maximum load you should put on your axles.
The tire industry has tables that cover the dimensions and load limits for tires for different levels of inflation. These tables have been around since the ’70s. All tires sold for highway use in the U.S. are required to be capable of passing a number of different strength and durability tests. The test conditions specify both load and inflation levels for the different tests.
The RV company has the responsibility to provide the information on the certification sticker such that the specified tires are rated to support at least 110% of GAWR when they are inflated to the stated inflation when the tires are at Ambient Temperature, i.e., “cold”.
You didn’t offer what tire engineering experience you bring to this discussion, so I don’t know how you arrived at your conclusion that 65 psi cold (ambient) was “too much.” But I sincerely doubt that the RV company would select LR-D tires if that level of load capacity was not needed.