A LOT of replies to tire threads recommend running the trailer (and I assume also car/truck/motorhome) at sidewall max psi instead of the dataplate psi. Why?My trailer tires have a max psi of 120. The trailer dataplate tells me the correct psi is 80. So I follow the manufacturer recommendation 80psi. I figure they know better than anone else what's 'right' for my trailer.What benefit(s) would I get running sidewall max 120psi?Same with my car & truck. Dataplate psi is about half the sidewall max. There may be a noticeable savings in fuel mpg running tires at sidewall max but the ride would probably be so hard as to be quite uncomfortable and I would assume tread wear would be much quicker. And I'd also assume there would be problems with the tire maker if I tried to make a warranty claim while running sidewall max instead of vehicle dataplate psi.

Benefit is (slightly) improved fuel mileage. But the cost is uneven tire wear leading to early replacement (not an issue on RVs which generally need new tires due to age long before the tread wears out); rough/bouncy ride (again, not so much an issue on a vehicle in which nobody is present and "stuff" is all tied down); slightly poorer traction/cornering ability; and slightly higher blowout risk.Bear in mind that there is controversy over the issue BECAUSE the differences either way are relatively small.

Here's an example:The company I work for has a fleet of vehicles we can use when going out in the field. One is a chevy 2500 long bed extended cab. Originally from the factory it came with load range c tires with a max PSI of 35. That's what the data plate shows on the door. When the tires were torn up on a rocky road, they were replaced with Load Range D tires. The sidewall shows max is 80 PSISimilar with a Jeep Cherokee. The tires were replaced with a higher load range tire.That being said many tire manufacturers on their websites provide charts which indicate the acceptable PSI based on the actual load.I always keep my tires inflated to the Max PSI indicated on the sidewall. I don't have the time to adjust the pressure depending on load I'm carrying.

120 psi?? What is the tire designation on the trailer tires and brand? Big difference in what to do between tire types and what they're on. Are the tires presently on the trailer the same as what's on the placard? They can be different and if run too low, serious damage from heat can occur.Go to RV tire safety dot com and read about ST tire inflation from a tire engineer.

A LOT of replies to tire threads recommend running the trailer (and I assume also car/truck/motorhome) at sidewall max psi instead of the dataplate psi. Why? Our RV trailer axles are close spaced and in the center of the vehicle vs say a truck with the axles at the corners with the front set steering into the corner and the rear set following. Now watch the trailer tires as they slide sideways (side scrub) around the corner. This action is trying to tear the tire apart....so tire experts and experienced trailer owners have found max sidewall pressure gives their tire the best shot at staying together. My trailer tires have a max psi of 120. The trailer dataplate tells me the correct psi is 80. So I follow the manufacturer recommendation 80psi. I figure they know better than anone else what's 'right' for my trailer. If you believe that then no use asking us anything :). Anyhow..... Somethings not right. I've never heard of a trailer mfg recommending derating a tire on their trailer by 25 percent. Doesn't make sense or It sounds like some one has upgraded a ST235/80-16 E tire at 80 psi to a much higher rated tire. If thats the case the trailers tire data plate will not reflect the right pressure. This from a good source when some one has over tired the trailer; rvsafety.com Tire Load and Inflation Ratings Note: Towable – Travel Trailer/ 5th Wheel owners Due to the severe use conditions experienced by tires when axles are very close together – tire industry experts recommend maximum (sidewall) inflation pressure for towable tires unless this causes a sever over-inflation situation (20psi+), often referred to as the ‘basketball effect’. If this is your situation allow a 10 – 15psi safety margin above the minimum required inflation pressure.

I think that comparing cars/trucks with trailer is comparing apples and oranges to a certain degree. I think the trailer tires should be closer to sidewall max pressures because of the stresses that the trailer puts on its tires. Seems to me a fully inflated tire will withstand cornering and scrubbing issues better than a tire that is softer and only partly inflated. But that's strictly IMO. FWIW however, Goodyear did have a notice on their website that recommended inflating RV tires to max sidewall pressures.

Tire Pressure - MAX vs DATAPLATE | Good Sam Community

23 Replies

myredracer
Explorer II
Jun 19, 2015
120 psi?? What is the tire designation on the trailer tires and brand? Big difference in what to do between tire types and what they're on. Are the tires presently on the trailer the same as what's on the placard? They can be different and if run too low, serious damage from heat can occur.

Go to RV tire safety dot com and read about ST tire inflation from a tire engineer.
the_bear_II
Explorer
Jun 19, 2015
Here's an example:

The company I work for has a fleet of vehicles we can use when going out in the field. One is a chevy 2500 long bed extended cab. Originally from the factory it came with load range c tires with a max PSI of 35. That's what the data plate shows on the door. When the tires were torn up on a rocky road, they were replaced with Load Range D tires. The sidewall shows max is 80 PSI

Similar with a Jeep Cherokee. The tires were replaced with a higher load range tire.

That being said many tire manufacturers on their websites provide charts which indicate the acceptable PSI based on the actual load.

I always keep my tires inflated to the Max PSI indicated on the sidewall. I don't have the time to adjust the pressure depending on load I'm carrying.
naturist
Nomad
Jun 19, 2015
Benefit is (slightly) improved fuel mileage. But the cost is uneven tire wear leading to early replacement (not an issue on RVs which generally need new tires due to age long before the tread wears out); rough/bouncy ride (again, not so much an issue on a vehicle in which nobody is present and "stuff" is all tied down); slightly poorer traction/cornering ability; and slightly higher blowout risk.

Bear in mind that there is controversy over the issue BECAUSE the differences either way are relatively small.

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Tire Pressure - MAX vs DATAPLATE

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