Horse trailer tire psi question

Haven’t used the Kingston 2 horse w/ dressing room in 8months. Going to check tire pressure as horse will be traveling in a few days. Now am confused- tires say 65psi, Tag on trailer says 40 psi. Am I misreading something?

Your current tires are most likely Load Range D and are rated for max 65 psi when cold. It should say all this on the tire. While you are examining it, find the four digit code and see how old they are. (first two digits are year, second two are the week of the year.)

The trailer may have been sold with lower rated tires, thus the lower pressure on the trailer plate. Load range C is usually 50 psi though, I thought.


I was told to use the PSI listed on the tire as the mfr of the tire knows best. I have a Euro trailer and the tires it came with (and trailer tag) said PSI 40. I couldn’t get the same tires here and the ‘trailer guy’ said to do what the tire says - so I do.

The PSI on the tire is the maximum the tire should be filled to. The PSI on the trailer is the Minimum based on the maximum weight the trailer is rated to carry. You should fill your tire somewhere between those two based on the weight you are carrying. There are charts for this, or you can kind of guess based on your trailers carrying capacity as compared to what weight you are carrying. Most important is that the tires on the same axel have the same PSI of air.


The maximum pressure on a tire is the bead-setting pressue when the tire is initially mounted on its rim. The trailer manufacturer hopefully has performed their own research to back up their recommended run pressure for towing. But given the wide range of types and brands of tires that I have seen on trailers (even identical new trailers on dealer lots may have different tires based on tire cost and availability at manufacturing time) I doubt that few trailer producers make the effort or spend the money to actually do that.

I go to the tire manufacturer’s web site or contact them for tire pressure advice rather than depending on online posts. The big ones like Goodyear are very good about responding. I have my own tire mounting and balacing equipment and have done this for years, and have learned a lot. I have about 80 tires on various vehicles on the farm, and owning tire repair and mounting equipment pays for itself over time.

I would be more worried about the tires being dry rotted from sitting so long. Be very careful

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That is only potentially valid if you haven’t changed the load range (meaning upgraded from the usually under rated tires some trailers come with). In truth I’ve never heard any trailer tire expert recommend under inflating a tire. They all recommend that trailer tires are always up to max psi for hauling.

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I work for truckers. They would disagree. There IS a reason your trailer is stamped with a recommended tire PSI and that it doesn’t match the tires, even though the tires came with the trailer. There is math involved, but it will prolong the life of your tires to fill appropriately to the weight you are hauling, BUT, for short hauls? Probably doesn’t matter.

I totally agree about short hauls, but high road heat/long hauls require top psi. Every trailer I have ever owned is listing the top psi of the load range tire it came with off the factory floor. If you change that load range, that number on your trailer isn’t worth the sticker it was printed on.

Sadly a lot of trailers come with the absolute minimum load range and rim size as the default tire and charge extra for what may be a better rim/tire for the intended use (sundowner and your history of tire blowouts, I’m looking at you). A lot of people don’t spring for the higher load range on the initial purchase because they don’t know and, damn, the add ons start to really hit the pocket book. And even if you do spring for the more suitable tires, depending on what you do, more might be better. Most of my trips are 7+ hour trips and even though my BP came with 17" E’s, after 3 years when replacement time came and I looked at how the tires handled the wear and tear, I decided to moved up to Fs that were rated for higher speeds because of all my highway time, the fact that the trailer is fully loaded and there’s just no time of year, even winter, where the GA-FL roads aren’t hot.

If you are just doing short hauls locally, it’s less important, but even one couple hour trip in the summer and load range, psi and speed ratings matter if horses are in board

Just to add to the discussion, you really need to check tire pressures EVERY time you hitch the trailer. Cold versus hot days, WILL change the tire pressure readings when checked. Hauling trailer with pressure below the rating, is very hard on the sidewalls. Sometimes you need to let a bit of air out, to get down to the number on the tire.

Using the correct tire pressure lets tires wear better, less likely to have problems enroute.

We always get our trailer tires balanced, to improve tread wear, increase fuel mileage, make hauling easier.


So, interestingly enough, I called 5 trailer dealers ( who sold horse trailers) and there was not one definitive answer. Some said correct psi was the number on trailer, others said the tire number was correct. Somewhere in between I guess.
Thanks for your input.

Your experience with trailer dealers brings up the difference between maximum tire pressures and optimum tire pressures.

Tires have both maximum pressure ratings and maximum load ratings. You will likely find that the load ratings of 4 trailer tires added together is less than the loaded weight of the trailer itself, so maximum tire pressure is not optimal. This is a factor that engineers with car, truck, and trailer manufacturers consider in arriving at the recommended tire pressures they assign and post.

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