Since I had heard numbers anywhere from 30-37psi I went straight to the source.

I called BFG Tire Care & Maintenance and spoke with a few of those guys, mainly cause I had some questions about some things but the reason I called them was to get a recommendation for tire pressure on my 285's.

I told them my year model, what my stock tire placard said and the size of the tire and wheel that I am currently running.

They put it in there little calculator thing and she said I should run 35psi all around for optimal tire wear, ride quality and handling.

Here is her answer per the transcript of our conversation:

"The original tires on your vehicle P225/75R15 inflated to 29psi carried 1720 lbs because this is a larger vessel it needs more air we recommend that the
LT285/75R16 are inflated to 35psi which will carry 2130."

She went into more depth of how the weight is calculated and how they come up with the recommended tire pressure but honestly all SHE did was put it in the calculator program on her computer and it spat all of the information out. Apparently the computer takes into effect the year model and all of that jazz.

I thought it was pretty neat.

Anyway, I thought this would be some good information to have on here.

Later,

Fink

 

Cool man.

 

when i ran my at's at 40, the ride was absolutely atrocious

shame they dont have that calculator on the web

 

I'd hate to question the tire mfgr but... They are right that a bigger tire holds more air, volume. Also a larger tire with more volume will hold more weight. They proved that also by saying that the bfg with 35psi will carry 2130#. If you need to increase your safe laod carrying capasity then a larger tire with a higher max psi will raise your safety margins. It has been my experience that a larger tire will require less air than a smaller tire to carry the same amount weight. I would call them back and ask them what psi should you run to match the stock psi/capasity (29psi/1720#) Doing the chalk method you can check if your footprint is ridding flat.

 

I always do the chalk test, inflate the tire to about 10% less than the total and draw a line with chalk across the tire. Then drive a bit in a straight line and see if the chalk wears evenly, if not adjust your pressure.

I have found its about 10-12% less than the recommended max psi...

 

problem is pressure is not a measure of volume... yes you need more air but doesn't mean more psi... I hope the calculator is better than her understanding of physics..

tempature and pressure however are closely related... pV = nRT i don't know why this sticks in my head so well...


Anyway.. from a cold morning tire pressure to the significant heat generated by friction from driving - nit picking between a few psi is kinda silly...

 

I think for that size thats a little low, I feel the lower is better if you do alot of driving on dirt roads etc. But out on the highway I run like 40-45 lbs.It all depends on what your hauling and how you like your ride. I noticed my 285 BFG AT's really buldge at the side walls at 35 lbs. and really look low. I guess it just depends on wear too. Keep an eye on em' and adj. as needed.

 

The big fat tires on ATVs only have 3-5psi and hold alot of weight. The 6x6 can carry 1000# in the rear bed.

 

I've heard so much damn stuff about tire pressure, its rediculous.

But, the last 3 people have told me to run at 35psi. This is coming from:

1) A mom and pop tire company
2) A retired auto-shop teacher
3) A full time professional mechanic at a dealership

Now, hearing this from the manufacturer makes me think I'll stay at about 35 psi.

 

35-40 IMO...I run my MT/R's at 40 and they do just fine.

 

Something else to think about. Two bicycles, one a road bike and the other a mtn bike. The road bike with the 1" wide tire runns with 125 psi the mtb with 2.25" wide tires runs 35 psi. The volume is much greater in the mtb tire carrying the same weight.

Also the lower psi you have in a vehicle tire allows that tire to roll in corners much easier alowing the shoulder of the tire to wear faster.

 

I run my 285 BFG MT's at about 45psi. I also find that mine really buldge at the side walls at 30-35 lbs. Also I find that if I leave them at 30lbs and go for a long ride, the sidwalls actually seem to get hot. I spoke to someone at toyota and they said that this is from the sidewalls flexing and that the heat can lead to a blow out. TRUE?? At 45lbs they do not seem to get as hot. It reads MAX 65PSI on my sidewalls.

 

I have almost no buldge at the sidewalls, a little buldge is okay...it just means the tire is touching the ground at the sidewalls, zero buldge would mean it's riding high in the center.

I didn't mean to start a debate, it just confirmed that my 35psi in my tires is correct...I've always ran 35 and just wanted to check.

I agree, her explanation of the physics involved was a little sketchy but she wasn't hired for that, lol. She knows how to use the computer and the calculator and she was really nice...lol.

Fink

 

I've had BFG ATs on my 4runner for 80k miles. I have always run them, with and with out a load, at 30 psi. My last set wore out at 75k, totaly dead even tread.