AT or MT Tire Pressure on a Trailer

[brian0128]

How do you determine your tire pressure for your AT or MT tires on your trailers? I am currently running General Grabber LT235-75R15 tires, Load Range C, Load Index 104/101S, 50psi max inflation, with 1985 lbs max load. My calculations are showing a recommended pressure of 18psi which seems low.

I was using the following formula:
Weight at the axle divided by the max load stated on the tire multiplied by two (since there are two tires on each axle). Add 20 percent to that number for a safety margin. Now multiply that times the max load pressure stated on your tire. This number gives you the street pressure for your tire.


Weight at axle
________________ = A
Max tire load x 2
A x 1.2 = B
B x Max load psi = C (your street pressure)

Manley ORV axle weight 1200 lbs.
1200lbs
________________ = .30
3970
.30 x 1.2 = .36
.36 x 50 psi = 18 psi tire pressure

 

[USStrongman]

Considering they are being pulled and provide no steering or drive benefit, I run mine higher. 34-36psi on a 65lb maximum. I want the trailer to move across the road and not produce unintended drag. MT's on a trailer I think are overkill. They weigh more, wear faster. Again, since they are not driving or steering I dont see the need for an MT. Now, if the road I am on is heavy washboard, full of rocks, undulating, then I might run lower, however, based around the type of suspension you have. Solid axle with minimal articulation, I'd run softer. IRS with moderae to longer articulation, I'd run harder, but again, based on the trail type.

 

[smritte]

My M-100 is about 1400 loaded.
25 psi wears the center a little, 20 gives a good pattern.
I tend to run 25-30 on the street for less drag and 15 off-road to soften the shock on my cargo.
Tire size is a 10.5 X 33 bfg at.
By your calculation, my tire pressure should be about 20. Not bad

 

[Odyssey USA]

I’m not towing off road but my first thought is lateral traction so whichever tire does best there.

 

[Shakes355]

It seems low only because your tires are overkill. 18psi should be fine. 6 ply tires with a combined 1200lbs won't flinch. You can bump it up to 20 if you like but you may feel it wander a bit. The sidewall won't flex enough with that load to cause an overheating condition and running down pavement for a spell will increase the pressure a couple pounds anyway as it heats up.