Trailer tires pressure

A

alainP

Member
I now have 10 ply rated tires on the trailer, indicated max pressure is 80 psi.
What is the consensus on this? Always max pressure no matter what? Season and temperature dependant? Trailer loading dependant? What range to stay between if less than max inflation? I'd like to get started on the right foot with these tires.
Alain Provost
C-Dory 25 Cruiser
 
I run the max pressure shown on the sidewalls in my trailer tires, and I believe that is the standard recommended practice. Colby
 
The recommended standard for trailer tires is as per the chart for that tire, not the max pressure. The trailer fully with the boat and gear should be the starting place.
 
My experience is that most of the tires on trailers coming out of a dealership are barely adequate for the max load of the trailer. So yeah, a lot of times maximum PSI is probably for the best since so often the trailer under the boat is also the minimum they could get away with. Yours might not be this way at all and you may not need maximum pressure for your load. That said, maximum pressure won't hurt anything except the ride....and the tires could wear more in the middle than usual, but all that is very debatable as well with the many variables in play with this. Without knowing the actual weights and measures, it is impossible to give a solid recommendation.
 
Etrailer: We recommend that all trailer tires be inflated to the max psi stated on the sidewall of the tire. If the tire is under inflated, the weight capacity is lowered to an unknown amount for that tire.

Les Schwab: Check tire pressure before you use your trailer. Keep your tires inflated to the maximum PSI branded on the sidewall.

Discount Tire: Trailer tires should be inflated to the maximum inflation designated on its sidewall in order to provide the full load carrying capacity

Carlisle Tech sheet: Was a pdf I couldn't copy and paste from, but it also said to inflate trailer tires to max indicated on sidewall.

Just the first four trailer tire shops I came across...

And for many of us with dual axle trailers. If you have a blow out or flat, wouldn't you rather have the full load carrying capability of that other tire? I'm sticking with max PSI stated on the tire's sidewall! 10,000 miles on average each year, it's worked for me! Colby
 
I'm going along with Colby and the rest of the Max listed on the sidewall, IF you are running at full load capacity. I have a tandem Pacific, galvanized steel and it's rated at 6500#. I'm running at a shade over 5K generally, on GoodYear Endurance. From Les Schwab, IIRC, the max inflation pressure is 70 PSI, and they recommended 65 for my 5,300# load.

They also recommend deflating to 35 - 40 PSA depending on ambient temp if doing a long pull with the trailer empty.

Harvey
SleepyC:moon

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Most trailers are going to have to be max PSI because the dealer puts the heaviest boat possible on the lightest trailer they can. However, there are cases where max PSI is not ideal. My e450 motorhome is only 24 feet with no slides and rides horribly when the back tires are 80 psi. It makes sense they would recommend that PSI for much heavier and larger coaches, but my much smaller and 5k lighter RV has the same door sticker.....because it says e450 I'm guessing and they are worried I'm going to put fifty bags of cement on the floor or something.
 
T.R. Bauer":18wax60l said:
Most trailers are going to have to be max PSI because the dealer puts the heaviest boat possible on the lightest trailer they can. However, there are cases where max PSI is not ideal. My e450 motorhome is only 24 feet with no slides and rides horribly when the back tires are 80 psi. It makes sense they would recommend that PSI for much heavier and larger coaches, but my much smaller and 5k lighter RV has the same door sticker.....because it says e450 I'm guessing and they are worried I'm going to put fifty bags of cement on the floor or something.
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It has always made more sense to me to do what it says on the tire. The tire mfg knows the tire, how they built it and what it will take. The device with a door sticker, be it a trailer, RV, or even your car can put on their sticker whatever they want, but that does not mean that you have their recommended tires on your rig so how can they tell what pressure to put in your tires. They are prognosticating at best.

Harvey
SleepyC :moon

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I'm running Goodyear Endurance tires with tire pressure sensors. Max psi is 65 in the summer season I inflate to 58 psi. This is because by the time I have gone 20 miles they will be up to 65 psi. Later in the trip they might reach 68 psi. It bothers me to look at the display and see them hitting 75 psi. In early spring and late fall 65 psi is ok. I know there would be a margin of error that the factory would say is ok, but just try to get anyone to give you a straight answer on what that is. So how does everyone feel about running at over the max pressure?
 
Jody, the tire manufacturers are well aware of tires increasing pressure while running or in the sun. That's why they state not to lower the pressure after running on the tire or if it's ambient temperature is hotter, like when it's setting in the sun. Some other issues I don't think many think about. Loading or even levelness may effect the weight each tire is carrying. With less PSI you will get more sidewall flex, which isn't going to help maintain the trailer running straight (think fishtailing). Over and over again, I see both tire manufacturers and trailer manufacturers say fill to max psi indicated on the tire's sidewall. I'm only talking about ST rated tires. Colby
 
colbysmith":29t4jtb0 said:
... With less PSI you will get more sidewall flex, which isn't going to help maintain the trailer running straight (think fishtailing). ...
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More sidewall flex also means more tread flex. The more flexing the hotter the tire gets. If nothing else, hot tires are bad for tire life.
 
Do what you want....the load rating for the ST 225/75/15E is 2500 pounds per tire at 80 PSI if you're running them as a dually - single gives a couple hundred pounds more per tire. At 80 PSI and a light load they are quite jarring and accelerate wear in other components. The load rating of my 315/75/16E BFGs on my truck at 80 PSI is 3860 per tire and if you run them there, you will feel every bump in the road in my 3/4 truck and will likely suffer from kidney failure. Again....to each his own, but like it or not tire inflation is relative to load. As Dr. Bob said, go look at a chart if you're in doubt.
 
Do what you want....the load rating for the ST 225/75/15E is 2500 pounds per tire at 80 PSI if you're running them as a dually - single gives a couple hundred pounds more per tire. At 80 PSI and a light load they are quite jarring and accelerate wear in other components. The load rating of my 315/75/16E BFGs on my truck at 80 PSI is 3860 per tire and if you run them there, you will feel every bump in the road in my 3/4 truck and will likely suffer from kidney failure. Again....to each his own, but like it or not tire inflation is relative to load. As Dr. Bob said, go look at a chart if you're in doubt.
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I believe the single tire rating for that tire is more like 2830 lbs. I don't know of any boat trailers that run dually's. The reason for the lower load rating when running them as duals, is to keep the flexing sidewall from rubbing each other. If you can find a tire inflation guide for the tire you have, great. But it's only going to be accurate if you weigh each tire under load to get an accurate weight. Which will change every time you move stuff around in the boat, add fuel or water, etc. The simplest method really, is too just follow the advice of almost all tire shops and manufacturers to run the maximum PSI shown on the sidewall of the tire, when running ST tires. We're not talking LT or P tires, which are not made for trailers. Nor are ST tires made to be ran on passenger vehicles. In the long run, you will do more damage running an under-inflated trailer tire. But as you say, to each their own. Colby
 
Salmon Fisher,
I downloaded and printed the Load/Inflation chart and looking at it (first chart up top for ST tires) I get a bit confused.
For the ST225/75R15:assuming a total load of 7500 lbs and assuming again it would be equaly distributed on each four wheels, the chart gives me a recomended inflation of 40psi.. am I looking at this right?
 
jkidd":1iwyzaks said:
I'm running Goodyear Endurance tires with tire pressure sensors. Max psi is 65 in the summer season I inflate to 58 psi. This is because by the time I have gone 20 miles they will be up to 65 psi. Later in the trip they might reach 68 psi. It bothers me to look at the display and see them hitting 75 psi. In early spring and late fall 65 psi is ok. I know there would be a margin of error that the factory would say is ok, but just try to get anyone to give you a straight answer on what that is. So how does everyone feel about running at over the max pressure?
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Jody, Thanks for that info. Good to have. (No TPM's on my trailer - But I do have them on the motorcycle.) Amazing on how the temps and pressure varies, rapidly and considerably.

:?: Are not the tire inflation pressures from either the charts or the sidewall stated for cold tires?

Harvey
SleepyC :moon

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Yes, you are correct, that is for 1,880 lbs per tire, so approximately 7,500 lbs total. What is the maximum inflation stamped on the sidewall for, I'm assuming, your Goodyear Endurance ST tires?

40 PSI seems low to me. I would probably go with closer to the Maximum inflation for each tire since you want the side walls to be well supported as others have commented.

Have you weighed your boat on the trailer with your typical load? If you are at 10,000 lbs then you would be running a minimum of 65 PSI.

To get a true reading of tire weight, you would have to weigh each tire with your boat loaded on the trailer. Honestly, I don't know anyone who has done that.
 
Ah! I found something interesting looking at the Carlisle Tires Trailer Tire Service Guide Line,
Under an identical chart that the one for Goodyear Endurance there was this paragraph:

" The above table DOES NOT endorse the reduction of air pressure.
It is to be used as an exampleof the relationshipbetween air pressure vs,load or lack there of. Carlisle Tire & Wheel only recommends and only warrants tires maintained @ the max air pressure while in service. The above tableshows the relationship between air pressure and load capacity for popular sizes of trailer tires. The capacities apply equally to radial and bias versions, The letters following some capacities indicate the load range."

There is more after that regarding Maximum PSI,

"Maximum load range is attained only when the tire is at its maximum air pressure. There is no advantage to taking air out of the tire, With maximum pressure the tire will perform and wear better and you will get better gas mileage. Reduce the PSI and you compromise the functionality of the tire."

well.. that clarifies a few things for some...
 
I have not weighted the boat and trailer, never found a convenient way or time to doit. Getting the boat out and back in is a bit of an undertaking.
I think ~ 7,5 K lbs is a fair estimate with little fuel and no water?
 
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