Tire pressure thread

[james02]

Soooo, after spending some time Sunday with some good friends and fellow members there seems to be a bit of debate at to what pressure to run at...What tire size/ street pressure/ trail pressure does everybody run at??

[bartonmd]

There's been a couple threads on it. It really depends on the specific tire, its load rating (sidewall strength), and it's diameter and width. The more contact patch, the less pressure you need. The harder the sidewall, the more pressure you need to get even contact pressure (and wear) across the tire. If you call the tire mfg and tell them what you're driving and what the tires are (size and specs), they'll (At least BFG will) tell you the pressures to run in them.

For instance, 245/70-17 BFG AT in load range E on my TB run 45PSI, per BFG, and have worn well doing so.

Mike

[HARDTRAILZ]

Run a chalk test for street pressure.

Offroad...I could notice a loss in traction if I stayed above 15 PSI.

[v7guy]

I just ran the pressure that seemed to give an even contact patch on the road. Seems to be working fine, I'm at 45 lbs if i remember right.

[Moots1288]

Im running 27-30 lbs. in my goodyear MT/R's and they have even wear on the tread.

[navigator]

I'm running about 40lbs on my Toyo 10Plys. If I run more than that they ride a little rough.
I haven't run a chalk test yet but after 5 mos they are wearing even.

I usually run my tires at about 18-25 when I air down depending on the situation. I've not needed to air these down yet.

[jonbo2002]

I run at 38lbs street in my BFG Rugged Terrain. Haven't had to air them down yet but will go down under 15 next time I take the sand trails by my property up north, lol had to back up a couple times and take a different route because I was sinking in the sand and didn't have my winch or anyone to pull me out. Wasn't going to take a chance my first time out there.

[boog2006]

Had my first obvious loss of traction due to tire pressure yesterday...on my lawn mower.

I mow my ditch with a zero turn Gravely 42". I go up the ditch instead of with the ditch (not recommended but works for me). I noticed that the tire pressure was low when I went to start mowing. Both rear tires were down at 10 psi vs 22 psi rating. So, I increased to the recommended setting and took off. I almost didn't make it up the ditch a few times due to the traction decrease. Now I have to find the sweet spot as 10 psi was pretty low.

I'm now a believer of airing down.

[DirtyBacon04]

BFG A/T 285/75 16, i run 35 on road

Offroad: 20 psi in front, 16 psi in rear.

[james02]

BFG A/T 285/75 16, i run 35 on road

Offroad: 20 psi in front, 16 psi in rear.

Interesting....Why the difference??

[DirtyBacon04]

give front and rear axles different traction. Some terrains are better with harder tires, but large hard obstacles usually require lower pressure. this just gives me more universal applications. Always try to think of the 4x4 as a push/pull system (front axle pulling, rear axle pushing). If i'm in an obstacle that would benefit from high tire pressure, at least I have two tires with that pressure, and vice versa.
I read an article in off-road mag about it, and it alll clicked for me.

[TangoBravo]

I run treadwright guard dogs on both my rigs. Seems 43lbs on street is what mine like, off road I run anywhere from 8-12lbs

[Moots1288]

I run treadwright guard dogs on both my rigs. Seems 43lbs on street is what mine like, off road I run anywhere from 8-12lbs

you rock crawling with that 8lbs?

[SmokeyMcBlazer]

BFG A/T 285/75 16, i run 35 on road

Offroad: 20 psi in front, 16 psi in rear.

Do you think that the 4lbs difference between the front and rear tires could reduce the diameter of the rears enough to put undue stress on you're 4WD system? I don't think I would be running with two very different air pressures in 4WD for any amount of time.

[ErikSS]

BFG A/T 285/75 16, i run 35 on road

Offroad: 20 psi in front, 16 psi in rear.

Do you think that the 4lbs difference between the front and rear tires could reduce the diameter of the rears enough to put undue stress on you're 4WD system? I don't think I would be running with two very different air pressures in 4WD for any amount of time.

I think it depends on the conditions. I go to Silver Lake Sand Dunes. When running in beach sand all day, I reduced my tire presures to 10 in the front and 7 in the rear. I would NOT run it on the road that way. I wouldn't even run it that way on a typical trail... But different offroading calls for different tire pressures.

The more solid the ground your on, the more even you'd want your front and rear pressures.

[DirtyBacon04]

I think a important factor is weight in the vehicle. If you have an empty cargo area but full front armor, I think you'd want the rear tires lower to help offset the tire deflection/weight ratio.

[Trail X]

Do you think that the 4lbs difference between the front and rear tires could reduce the diameter of the rears enough to put undue stress on you're 4WD system? I don't think I would be running with two very different air pressures in 4WD for any amount of time.

While it does change the effective radius from the center of the wheel to the ground, it does not change the circumference of the tire. So the 4WD system would see no effect.

[HARDTRAILZ]

While it does change the effective radius from the center of the wheel to the ground, it does not change the circumference of the tire. So the 4WD system would see no effect.

So my 4x4 will not have issues if I run 40 psi in the front and 10 psi in the rear because the circumference of the tire is the same?

[Trail X]

In theory, your wheel still travels the same distance per rotation no matter the pressure. Now there may be some tread scrubbing and as a result minor rpm differences when such a drastic difference is present, but I do not believe there would be a major drive line bind.

[ErikSS]

In theory, your wheel still travels the same distance per rotation no matter the pressure. Now there may be some tread scrubbing and as a result minor rpm differences when such a drastic difference is present, but I do not believe there would be a major drive line bind.

I can't say I agree. If the distance between the center of the wheel and the ground changes, the circumference must also have changed.