I thought a good discussion here could be in regards to airing down tires vs. the different regional terrain.

For example, here in AZ where we have sharp, ledgey (yeah, I know it's not a word) rocks and waterfalls, 12 to 15 psi seems to work best for just about any tire that is meant for off road. I have run BFG A/T's, M/T's and now Goodyear MTR's at these pressures with great results.

What works best in other parts of the wheeling communities? Please also describe your terrain as well...

Mike

 

I used to air my BFG AT's down around 15 or so, didn't really help as they were still AT's and the mud didn't care.

Now the MT/R's hang around 14 or so in the mud with decent results. I am afraid to go much lower with so much wheel speed.

On dry rocks I like 10 or 12, didn't get that figured out until later in the game in Colorado. Not too many dry rocks here. I will have to check some more rocks there later.

 

It's ledgy. And it is, in fact, a valid word.

As taken from MW: - ledgy /'le-jE/ adjective

By the way, same ledgy type stuff up here! Same PSI as you guys mentioned.

 

Usually I do 15 psi. Terrain around here usually consists of rocks and lots of mud.

 

Ive got my Staun Deflators set at 15 PSI. I run that on ledgy rocks, round rocks, sharp rocks, deep loose gravel, normal gravel, fine sand, coarse sand, corn snow, powerey snow, ice, dirt, steep dirt, mud, stickey mud, dry mud and everything else I find to drive on.

My tires, 32" MTRs, have fery stiff sidewalls and its hard to get them to fold over rocks. At 15 they tend to bounce some but i'm used to it. The only time I went below 15 was in ice racing on a frozen lake. I went to 11 in the rear and 13 up front. The front is heavier with the motor and everything. I wanted the front to be a slightly larger diameter to make them cover more ground in turns that the rears. It kinda worked but I still had tons of push on turn entry.

 

I currently have BFG MTs 31x10.5 and have found that I have rarely needed to air them down. In Arizona/Utah soft sand I brought them down to 20psi, but several days later did the same trail without airing down. I'm finding that unless I'm in really soft, soupy mud, the pickup usually doesn't doesn't need it, and also that the wimpy compressor I had purchased took days, not minutes, to bring them back up to the recommended 50 psi. I just purchased an on-board air tank so I will be less hesitant in the future to air down, but I'm still not sure the truckwill need it very often.

 

For stock tires, I ran 20PSI, and it made quite a big difference.

First time out on Pro Comp MT 31X10.50R15 I ran about 16PSI. That seemed to do well, and let the sidewall flex some. I may try lower next time (14, and then maybe 12), as I would still like to see some more flex in the sidewall. The trails around here seem to consist of mostly red dirt/mud which is very slippery with a high clay content. It takes a lot to free up that junk even from a full mud tire. We have some rocks, but mostly small ones that could cause punctures. I haven't been on any trails here yet with "ledgy" rocks!

 

Tire size is also a factor- I'm using 35" MT/R's-

For the local Nat. Forest Service trails, I usually drop'm down to 12 to 15 PSI to improve the ride and traction. At pressure's lower than that, they will bottom out on the rim when hitting holes of ruts at higher speeds. Most of the F.S. trails are between a 2.5 to 3.5 rating, w/ lots of ruts and washboard'd surface, loose rock. etc.

For the more serious terrain, I've found there's a huge difference between 12 to 15 PSI and 8 PSI- the contact patch gets substantially bigger, the tires wrap around stuff better, and they still stay on the rim pretty well without bead locks.

later

 

Good to see you here bud!

crawler#976 is a great addition to this community, a cool wheeler and a good guy. He's also got a pretty cool rig.

Thanks for contributing chief, hopefully I can get out there this weekend and watch the Pirate boys scar up a bunch of tubing!

Mike

 

Also if you go much lower than 12 you really loose a lot of ground clearance.

 

I have 37" MTRs and if I'm running something like Tahuya, a very easy trail system, I'll soften them to about 15 just to make the ride a little nicer. On tougher trails I go 8-10. I don't actually start to significantly flatten till I get below 8 lbs. To get in my garage I drop them down to about 3 in order to get the flat enough.

If I was on snow, I'd probably take mine down to 3, perhaps lower.

 

I've been out at Pismo Beach (sand dunes) and have air downed to 6-8 psi. I've seen people stuck when air-down to 12 psi and they managed to escape when airing down to 6-8. I would recommend driving on anything hard. Turning doesn't work as well especially is you don't have power steering

 

I start at 15 and work my way down from there for the conditions.

~15 - FS roads, mixed light/moderate obstacles
~10-12 Packed snow/ice/watery mud/packed sand
~8-10 Gooey mud, rocks
~4-6 Loose, deep snow, loose sand

At 4psi, the flotation is incredible. I can ride in feet of fresh snow, sinking less than the distance to my diff But you need to be prepared to reseat a bead on the trail.

 

...and I'd have no idea how to reset a bead on the trail!

This is a really good discussion going here. I'm still really green when it comes to offroading, so I've really only aired down to what people have told me to do, which has been 15-18 PSI or so. Its worked for me, both on trails like Hollister and the dunes at Pismo.

Without on-board air, we usually have to drive a bit to get to a gas station to air back up. I'm looking in to power tanks.

 

It can be done with a power tank, with practice, but for those of us who are not fans of tanks or who are "old-school", the starting fluid method is easy and reliable.

 

ohh, right, I think I remember someone posting a video of resetting a bead using starter fliud.


What would be considered a safe minimum PSI when you do need to drive on roads to air back up?

 

That will depend upon your tires, wheels, driving style and the conditions. Just remember that for every PSI you are down, you need to slow down even more. At 15 PSI, I will not go any faster than 40 and prefer much less.

Heat builds up VERY rapidly when your tire pressure is down and it can lead to unseen damage, particularly in the sidewalls of the tires. At less than street pressures, the only way to avoid this is to go slow and stop from time to time to allow the tires to cool.

Even before I had onboard air, I carried a portable compressor, prefering to spend the time with that rattling contraption rather than brave the risks of pavement travel when aired down.

There is no "safe minimum".

 

Thanks Rob, you pointed out a bunch of important things to think about.

 

You can also wrap a ratchet strap around the circumference of the tire to close the gap between the tire and the rim. This should allow enough air from sources other than a power tank to seat the bead. I've never tried it though.

 

That method may be easy and reliable, but not necessarily safe...

IMO airing down to 15-18 lbs is pretty safe in terms of not blowing beads, but it can still happen. This will soften the ride, and help with traction a little. In an offroad tire getting down to 12 pounds or so will significantly improve traction but with an AT tire the sidewalls may be too soft.

Another point here. It's less critical to air down for traction when you have lockers