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Tire Pressure During Off-Roading

flynhigh

flynhigh

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SO quick question...

Back in the day of Bias-ply tires we ouwld usually drop the air pressure some before going off-road.

Is that still applicable with the radial tires or not? And if so, how much do you drop the sir pressure by?


 
Yes, it's still quite applicable! I've run radials as low as 18 psi on trails. Going really low (I have a buddy with Super Swampers) like 8-10psi has limited returns on a radial tire because the tread surface is more rigid. Soft sand or mud is where you're going to really see the benefits... a bit wider footprint, and a chance for those side lugs to really bite. :)
 
Don't go too low or you will run the risk of breaking the bead. If you read about people airing down a lot they are most likely using bead-locks on their rims. Sand and snow traction is really helped with this trick.
 
YES, forgot to mention bead locks! Steel is totally right. Also do not forget (you'd be surprised how many ppl this wouldn't occur to) to have some way in which to air them back up to street pressure when you're at the end of the trail! I have one of those little 12v pumps now. It works, although it takes FOREVER. Friend of mine with a more hardcore offroad rig is consiering building in an underhood compressor driven off the engine... that would be awesome! ;D
 
But Wait! There's more!
Many folks, not wanting to get stuck with near flat tires will also carry an old fashioned manual pump. The little electric jobs can break or just die (I know, got lucky and discovered this in camp). Not a pleasant thought. It's less important however if you are traveling in a group where everyone has a pump.
 
This thread, in particular Crexis' post, touches on something I have been working on for some time: an underhood compressor. I did not need one for inflating tires, but for an air horn. Shortly before I was to begin purchasing and installing one though, a friend had me look at the modification he did on his Ford F-450: instead of installing a compressor for his Rancho suspension, airbags, and gooseneck air hitch, he modified the vacuum pump beneath the hood with valves so that, when a valve was opened, it doubled as a compressor. Very ingenius, and very company, and extremely inexpensive. This thread belongs in a technical forum instead, but I wanted to post it here first, as it is somewhat relevant.
 
Boar-Ral!

More details please!! Let me know where you post it if you start a new thread! Was also pondering the ability to use air tools on the trail :)
 
Some of you have seen my pic's of playing in mud and water.... I haven't dropped my air, because these are normally short runs through the play area....

I am wondering if I should air down, when driving over the mtn rocks. ?I am afraid if I go down low, that my tires will have a better chance of getting a rock through them. ?I had to plug one tire after my Moab trip.... Chevy didn't put 6 or 8 ply tires on ?:mad:
 
On beach sand I've had mine down to 11psi. It was absolutely required to get over some of the dunes I went over. I first tried at 14psi but the 3 ton AV just got bogged down in the sand and started to dig in. At 11, the sides really bit in and climbed the dunes in 4 low with great ease. I've been out to the same place 3 times and so far no problems with the tire beads. :D
 
Yes, I Air Down When On Sand and/or Rocky Terrain, It Allows You To Get A Larger Tire Patch On The Ground And For Rocky Terrain It Allows Your Tires To Mold To The Surfaces As You Crawl Over Them, And Your Less Likely To Get Your Tires Cut Back A Rock.

Just Remember Not To Got Too Low, As Steel Mentioned Your Can Break Your Bead Very Easy After 15 PSI.

You Also Need To Watch Your Speed After You've Air'd Down, Don't go To Fast.

An On Board Air Pump Is Always Great To Have, Look At This Site http://www.justcompressor.com

Have Fun Off-Roading

BlackZ71
 
If anyone installs one of these (motor driven or electric) please let us know how it works for you and how expensive/time consuming the install was!

I don't have the time or money to pursue it immediately, but am very interested!
 
Ive seen contractors retrofit theer trucksW/old AC pumps & an air tank under the bed they had in excess of 4.0 cmf to play with... :B:
 
I looked into that (for an old 4X4 I had some time ago) and discovered that stock GM AC compressors won't work without modification because the refrigerant they use contains lubrication... well if you use them to compress outside air, they'll seize up eventually because they're not lubricated.

I heard somewhere that some of the really old AC compressors actually have a small crank case with oil built onto them... this would be ideal.

 
Crexis - a York compressor. ?;D ?They're found in old Volvo's and AMC's. ?(early to mid 80's)

Would anyone like to comment on sand driving? ?Is it absolutely necessary to air down?? ?To what PSI?

I'm not use to these "new-fangled" lower profile 17" wheels. ? ;) ?My blazer had nice 31" tires on 15" rims that I could air way down.

I'll be down at the beach for a week, all next week... Got my beach pass all ready to go - I'd just rather save myself a bit of trouble of airing up and down if I don't 'really' have to.
 
I haven't done any beach driving yet marc, but got into a sandy dry river bed a few weeks back... felt the back end get a little squirrely, but cruised right through it in 4hi with steady throttle without airing down. ?

Probably depends on the beach and the tire (I've got Mud Terrains on my truck). ?

As long as there is someone around to pull you out, just try it ?;D

Thanks for the heads-up on the York compressors... I'll remember that!
 
I don't know about this possibility, but when I had a 91 k5 blazer I found a bracket to install another ac pump. The pump was driven by the engine. It did have to be set up with some filters to get the lubrication out but with a tank it worked great.

Another option is the QuickAir 2, for most applications the QuickAir 2 is perfect without a tank. Air up time is faster without a tank. The only time I find a take useful is when using air tools or needing to re-set the bead on a tire.

I pull 2 jet skis out on the beach every weekend, I have the stock tires (will replace soon) and I air down to 12 psi. So far no problems.
 
kiteOregon: Thanks for the info! Do you have the Quick Air 2 in your Av? Where is it?

And welcome to the club! :)
 
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