Off-road tire pressures

[gregd]

What's a reasonable minimum off-road tire pressure and what is the worst that can happen?

I have a Dodge RAM 2500 with Hallmark Ute XS camper (the camper weighs ~2000 lbs loaded). The suggested tire pressures for highway driving are 60 psi front and 70 psi rear. I've been going as low at 45F/48R (hot) off-road and this is a great improvement. I hear people talking about running in the teens but what's the limit? I keep hearing people say experiment and see what works but I'd like to know a reasonable limit and what the worst case scenario may be.
At some point do you pop the tire off the rim? Can you rip, tear, or otherwise damage a tire off-road by running too low a pressure and rolling through some nasty patch of jagged rock?
Obviously your air up time increases as you drop down further but are there any other issues to consider?

 

[bob91yj]

In my Dmax with the camper I won't go much below 30PSI (315/70/16's, Load D) Biggest danger IMO is rolling the bead off of the wheel going through a turn.

In my Jeeps, depending on the tires/wheels I'm running I'll drop as low as 5PSI in the rocks (beadlocks and TSL/SX's).

 

[gregd]

Thanks. That was exactly the kind of info I was looking for.

 

[1stDeuce]

Depends the size of the tire too, as a larger footprint will carry more load at a lower PSI. I'm right there with bob91yj on both accounts... Though if we're talking about getting through some sand, I'll air right down if I need to, even with a load in the truck. (285's on a Dmax) It's amazing the difference even just getting down to 40psi will make if you're running stock size tires, even with no load. By the time you're at 30 empty, all signs of wheelhop in soft terrain are gone. On a stock GM, anyway. (lift blocks on a dodge or Fffford seem to cause a fair bit of hop even at lower pressures sometimes.)

It's all about driving respectfully for the pressure you have in the tires...
chris

 

[GpnAZ]

airing down

I have a 2008' Dodge PW with a FWC Hawk and loaded weight is about 7300 pounds. My tires are 35" BFG KM2s. If I have a lot of dirt road or trail ahead of me (at least 20 miles) I'll air down to 20 pounds in the front and 25 pounds in back. I have done this numerous times and never had a problem. I believe my owners manual states to never go below 18 pounds(of course thats unloaded). Do what is comfortable for you and your driving conditions.

Mark

 

[Regcabguy]

I lowered my 285-75-17 Toyo Mt's to 40 psi in Utah,but 30-35 psi would have better. The roads I was on were similiar to Baja service roads I'm familiar with. I've got a portable Valair pump which reinflates all four to 60 psi in less than 15 minutes.

The Toyos have extremely strong sidewalls and I'm real confident with them with the vehicle weight being 9000# with two occupants and a wet popup. They are mounted on the factory aluminum forged rims.

After experiencing numerous flats and a near catastrophic blowout with Bridgestone Load range D tires on my 2nd gen,I upgraded to Toyo E rated ones. A 50 psi tire just doesn't work for me on the Beast.

 

[dizzyspots]

I read a thread at some point that added a bit of ?science to this question...suggestion was to load the truck as planned...(in the driveway)...measure the sidewall height...lower pressure to allow 3/4 (75%) of original sidewall height...record that pressure...when you get to the "air down" point in your travels..use that pressure as your airdown PSI just my 2 cents

 

[grimbo]

4psi rule works for me.

Basically set your pressures drive for about an hour and check them again if they have changed by more than 4 psi you need to adjust them further.

I have done this for a few scenarios to give me a good range. Generally in the Patrol on 33s on road loaded up its approx 36psi, dirt roads slower speeds about 18 , sand and snow 12-14psi.

My Suzuki Samurai on 34s regularly down to low single digits