Dirt road driving, what tire psi?

Status
Not open for further replies.

Nick1994

$100 site donor 2024
Joined
Feb 19, 2013
Messages
16,617
Location
Phoenix, AZ
This is for my grandfather's 1996 Jeep Cherokee. We head out to the desert several times a year, 100 miles of highway each way to the dirt road. Then about 60 miles of dirt roads. They're quite rough, but in some spots 45 mph is alright. No mud just rough rocky roads. Would like to soften the ride and gain some traction while I'm at it. Also reducing the chance of a puncture

It currently has a little larger than stock 235/75-15 BFG All Terrains on it. I run 36 psi on the road, have always kept the pressure the same on the dirt roads but it's a bit rough.

I have a portable compressor now, so right before getting back on the highway I can spend 5-10 minutes pumping the tires back up.

So what pressure do you guys think? I don't want them too low.
 
Maybe as low as 15 psi. I remember lowering my dads truck tires to 10 or 12 psi when I was a kid. Was pretty neat to stick your head out the window and watch the tire form to the terrain and have easily 200% more traction than a fully aired up tire.

Get you a portable air tank to make fill up a LOT faster at the end of the trail.
http://www.homedepot.com/p/Husky-10-Gal-Portable-Air-Tank-CT10H/202528456

You'll also want a spare tire, and some tools to re-seat a bead if your tire comes off the bead. You'll need a ratchet strap and air tank to re-seat the bead. You can sometimes use a flammable and a lighter to re-seat the bead.
https://www.youtube.com/watch?v=n6CfDmaEcdc
 
I usually drop the tires on my Jeep to 18-20 off road. If you have 7'' wide wheels (which I believe are factory) and 235 tires, you will have bead issues once you get down to 15. I've debeaded a few times at 15. Haven't had issues other than when I jam something into the bead if i'm playing in mud or something.
 
I always run the tires at the PSI recommended for the load when driving unimproved roads at highway speeds, sometimes steering with the throttle up to 90 miles per hour, almost never touching the brake, in my old careless days. One particular highway I drove at least twice a year was 320 miles of gravel, rock, packed sand, and if wet, mud. In about 80 trips, I only had one flat tire, where a rock the size and shape of a man's two fingers went right through the tire and rattled around inside it until we removed the tire from the rim. But I never lowered pressure for traction or handling below what my load suggested I run.

I understand the low pressure thing, but to me it's dependent on the tire and wheel you are running. For something that is reasonable on paved roads, I don't see why you would do it. If you have wide wheels and off-road only tires, well, of course.
 
I think you're more at risk of a puncture with a soft tire as the sidewall is more vulnerable. I'd stay w the recommended pressures.
 
Originally Posted By: bigt61
I think you're more at risk of a puncture with a soft tire as the sidewall is more vulnerable. I'd stay w the recommended pressures.
his bfg tires are designed to be ran at lower pressures in off road conditions. I have ran low pressures for 35 years and only had 2 sidewall flats.

Imo a soft tire allows the tire to flex where a hard tire gets ripped.
 
Last edited:
Originally Posted By: Nick1994
This is for my grandfather's 1996 Jeep Cherokee. We head out to the desert several times a year, 100 miles of highway each way to the dirt road. Then about 60 miles of dirt roads. They're quite rough, but in some spots 45 mph is alright. No mud just rough rocky roads. Would like to soften the ride and gain some traction while I'm at it. Also reducing the chance of a puncture

It currently has a little larger than stock 235/75-15 BFG All Terrains on it. I run 36 psi on the road, have always kept the pressure the same on the dirt roads but it's a bit rough.

I have a portable compressor now, so right before getting back on the highway I can spend 5-10 minutes pumping the tires back up.

So what pressure do you guys think? I don't want them too low.


As a general rule of thumb, I air down to 50% of my road pressure. In your case, that would be from 36psi down to 18psi.

HTH
 
I don't drop psi off road. Where possible, speed will make the ride tolerable.
 
Originally Posted By: bigt61
I think you're more at risk of a puncture with a soft tire as the sidewall is more vulnerable. I'd stay w the recommended pressures.


Never driven in the desert I imagine? You hit a rock at 45 mph with 36 PSI and you WILL destroy the tire. You will separate the belts and get a bulge in the tread. Every time. It is 100% proper, and customary, to air the tires down for real off road driving. Not a gravel road from here to there, but a real off-road trail with hills and rocks and whoopty doos.

Also, its amazing to see how much more traction a vehicle has simply by airing the tires down. Some places you will never go with fully aired up tires. Period.

Its also much easier on the suspension (and kidneys) with 18 psi vs 36 psi.
 
Yikes. Those pressure are a bit low.

I say that because my portable compressor is battery powered, I have 2 batteries. It last quite a while but I worry they might die before the tires are all pumped up.

What about 25 psi? Will it help?
 
Originally Posted By: Nick1994
Yikes. Those pressure are a bit low.

I say that because my portable compressor is battery powered, I have 2 batteries. It last quite a while but I worry they might die before the tires are all pumped up.

What about 25 psi? Will it help?


If you're worried about your batteries going flat, run the compressor with the vehicle runming.

You just need to experiment to find the right pressure. Drop 5 psi at a time, drive a few miles, repeat until you're happy.

Nobody can tell you the exact psi for your exact vehicle on your exact dirt road!
 
Originally Posted By: Nick1994
Yikes. Those pressure are a bit low.

I say that because my portable compressor is battery powered, I have 2 batteries. It last quite a while but I worry they might die before the tires are all pumped up.

What about 25 psi? Will it help?


Just so I don't make a fool of myself with an incorrect assumption ...

When you say your portable compressor is battery powered, you do mean it is powered by a cable connection to your vehicle's 12-volt battery, right?

You are not talking about a handheld compressor that runs off an internal battery, right?

You are not talking about something like this, right?

PortableCompressor_zpsqj12dfk5.jpg


Because if you are, then I suggest you leave your tires inflated to normal road pressures and adjust your driving style to best cope with your dirt roads.

HTH
 
It's a Ryobi One+ inflator. Powered by an 18V Lithium battery. I have 2 batteries.

It works great; just unsure if it can pump that much air for 4 tires. Maybe I'll try it at home first.
 
Originally Posted By: Nick1994
It's a Ryobi One+ inflator. Powered by an 18V Lithium battery. I have 2 batteries.

It works great; just unsure if it can pump that much air for 4 tires. Maybe I'll try it at home first.


Better not to air down your tires. It is doubtful your inflator could handle the task; but even if it could, you'd be at it all day.

HTH
 
Originally Posted By: Nick1994
It's a Ryobi One+ inflator. Powered by an 18V Lithium battery. I have 2 batteries.

It works great; just unsure if it can pump that much air for 4 tires. Maybe I'll try it at home first.


There's plenty of juice in two batteries. Or you could buy a $10 12v compressor as backup.
 
Originally Posted By: Nick1994
It's a Ryobi One+ inflator. Powered by an 18V Lithium battery. I have 2 batteries.

It works great; just unsure if it can pump that much air for 4 tires. Maybe I'll try it at home first.


You're going miles from civilization, right? Buy a 12V pump, if not two. Leave in vehicle (along with the usual roadside repair stuff).
 
Status
Not open for further replies.
Back
Top