Should I Use the PSI Rating on the Trailer Tire or the Rating on the Trailer Load Rating Label


I was told by big tire co. Never go by tire always go by inside door pressure. My trailer on side panel says 50 psi. Showing I go by trailer recommenation?


Expert Reply:

Typically the psi rating on the trailer tag should match the psi rating of the trailer tire, but it is not uncommon for trailer manufacturers to make last minute changes and go with a tire that has a higher load range, which means it will also have a higher psi rating.

We and our tire manufacturers always recommend using the psi rating on the tire for a couple reasons. First, the load range listed on the tire was tested at the psi rating listed on the tire. If you go with a different PSI, your tire's weight capacity will be an unknown. Second, if you were to ever have a tire failure under your warranty period and the manufacturer found out you were running at a different pressure than what is stamped into the tire, they will void your warranty immediately.

I don't know how old your trailer is, but another thing to consider is that the Recreation Vehicle Industry Association (RVIA) recently made a change that required trailer manufacturers to have a higher safety margin between the Gross Vehicle Weight Rating (GVWR) of a trailer and the weight capacity of the tires. In response to this, some tire manufactures simply increased the psi rating on their tires to achieve a higher load rating, after testing presumably. It is entirely possible that this change was not reflected on the trailer's specs tag.

Trailer tire manufacturers do not follow the same principles that automotive tire manufacturers follow when it comes to using varying psi ratings for tires. Companies like Michelin and Firestone for example will list a range of psi ratings and their corresponding weight capacities, but most trailer tire, or ST, tire manufacturers like Westlake, Carlisle, etc. only give one psi rating and load range and this is because trailer tires are manufactured differently. Trailer tires are built with stronger sidewalls because their main purpose is to support vertical loads on trailing axles versus automotive tires that are used on drive and steering axles.

One other point that I would make is that while trailer manufactures will road test their trailers, they do not specifically test for the best psi rating once the tire is mounted to the trailer. According to our trailer tire manufacturers, who are OEM suppliers as well, the trailer manufacturers abide by the psi rating stamped on the tire when inflating their tires on the production line.

expert reply by:
John H

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