Can I run my LR-E at 65 psi, or is this overloading the tire?

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RV Tire Safety
with RV tire expert Roger Marble

As trailer owners start applying the new Goodyear Endurance ST tire, many are discovering that for some sizes the Endurance tire is only available in a Load Range that is higher than their OE tires. Some are concerned about what inflation to run. I have even seen some claim that running an LR-E at LR-D inflation, i.e., not at 80 but at 65, that the “tire will be overloaded, heat up and fail.”

While I understand some of the confusion, I do not agree with some of the concern or replies.

Tire load capacity is a function of the tire size and inflation level as long as you stay in the same “type” tire.  By “type” I mean P type, or LT type, or ST type, or for large RVs, “truck” type.


If you stay with the same type and use the same numeric “size” then the only thing left to change is the Load Range or “Ply Rating.” While I do not like using Ply Rating as it is an old and discontinued nomenclature, it may help for better understanding in this post for you to think of the old term.

Important Point. “It is the air pressure that supports the load NOT the Ply Rating.” This statement is supported for every tire made by every tire company in the world through the use of Load and Inflation tables. These tables show a size and then for different levels of inflation the load capacity of that tire when inflated to that level. You will never see a tire shown where an LR-D at, say, 65 psi can support 1,500 pounds and for the same size the same tire when having an LR-E rating shown a higher load capacity at 65 psi. Not even just 1 pound more.

So an LR-E can support the same load at 50 psi as an LR-C, or the same load at 65 psi as an LR-D at 65.

You will not be overloading the LR-E if you load it to the 65 psi rating shown for that type and size tire and inflate it to 65 psi as you would for an LR-D. Since you are not overloading the LR-E tire it is not going to overheat at 65 psi with the 65 psi load, so the LR-E tire is not going to “overheat” at 65 psi any more than the LR-D will “overheat” if it is loaded to the 50 psi load rating and inflated to 50 psi.

When going to a higher “Ply Rating” you can then increase the CIP which increases the tire Load Capacity, which means it will actually be running cooler because of the greater “Margin.” The higher inflation will also lower the Interply Shear, which may lead to longer tire life.

When making the change you do need to confirm the upper inflation level for the rim. The wheel manufacturer should provide that information. As an alternative, the wheel will have a max load capacity stated. Looking at the OE tire size that comes on that wheel, look for the inflation that corresponds to that load and I would consider that to be the wheel inflation rating.

Read more from Roger Marble on his blog at RVtiresafety.net.

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CY
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CY

I need a little help understanding exactly what CIP to set my Goodyear Endurance tires to. I have ST235/80R16 load range E. I recently had my tires weighed individually – axle 1 2962 and 2890, axle 2 3040 and 2875. The tag on the 5th wheel says CIP to 80. Should I run the tires at 80, or adjust each to the next higher PSI on the chart? This would put 3 tires at 65 and one at 70 PSI. Would it be OK to set all four tires at 70?

Roger Marble
Guest
Roger Marble

CY, A couple of important points. 1. You have a multi-axle trailer. As I have covered in my posts and on my RVTireSafety blog. that type of suspension increases the “Shear” forces on the tire belts that are trying to tear the tire apart. You can lower these forces a bit by running higher pressure. This post was aimed at those who discovered that Goodyear Endurance is only available in a Load Range that was higher than the OE tires. In your case that is not the situation. Your OE tires were LR-E with an RV company recommended 80 psi… Read more »

Cy
Guest
Cy

Thank you Roger. That’s what I was running, but with multiple pieces of information I wasn’t positive. You cleared up my confusion. Again, THANK YOU!

Tommy Molnar
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Tommy Molnar

I’ve been inflating my tires to the max psi shown on the sidewall for years. Both trailer and tow vehicle. Am I doing something wrong? I’ve only had one tire failure in 25 years of RV’ing.

Roger Marble
Guest
Roger Marble

Tommy without more details I would suggest you inflate the tow vehicle tires to the tire placard on the tow vehicle. 2. Inflate the trailer tires to the inflation on the trailer.
These recommendations assume you are running the OE size and Load Range tires. You can learn more by reading the posts on my blog.

Will
Guest
Will

It is a bit confusing, as in his previous post he says that if you have a tandem axle trailer, you should probably inflate the tires those multiple axle trailers to their sidewall indicated maximum cold psi to lessen shear and premature tire failure. But you are correct that having tires inflated to 80 psi to carry a 50 or 60 psi load will stress the trailer structure a lot more.

Roger Marble
Guest
Roger Marble

Will. If you have changed tire size or Load range you have to do some work. There is no one answer that fits all the different questions that get asked. I have posted answers for people that have changed just the Load Range and for people who have changed the size and load range. I have answered questions for people with lightweight single axle trailers and with heavy multi-axle trailers. Also answered questions from Motorhome owners. Each of these situations needs a slightly different approach. For the best tire life, I do suggest that multi-axle trailers run a higher than… Read more »

Cliff Downing
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Cliff Downing

While this is pretty much true, other aspects should be taken into consideration. Over inflating a tire for the load that is put on it then can easily cause increased suspension wear and Vehicle or TT structural stresses that decrease their life. A tire has a lot to perform beyond just carrying the load. A proper footprint for maximum braking and handling is provided by running the proper PSI for the load. Too high of PSI in the tire for the load on it can negatively affect tire contact with the road. The tire also has to compliment the suspension… Read more »

Roger Marble
Guest
Roger Marble

I generally agree with what you said. You will notice I did not tell the person asking the original question to run the LR-E 80 psi. His situation was a bit unusual but there are a number of others who will also discover that the size for their trailer only is available in higher Load Ratings than the OE tires if they switch to Goodyear Endurance tires.