Minimum tire pressure for off-roading

All I’m saying is it’s a trade off. It’s also situationally dependent. On some terrain the increased traction might be critical. In other situation it might be marginal.

I wasn’t advocating against airing down, just stating what’s probably obvious to most, that there’s a resulting small clearance loss. For me, with stock tire size and stock suspension, that means I’m only going to air down if it’s necessary. If you’re riding on 35’s with a decent sized lift, loss of clearance probably has zero impact.

 

That video is absolutely correct to get your tire pressure setup for optimal tread wear on the pavement with whatever load out the truck is set up with.

If mall parking lots are what you consider "off road", well I guess I can't argue with you in finding this video relevant.

Regarding true off road driving in sand, mud, rock, and snow, that video does absolutely nothing for telling where your PSI needs to be for improved traction.

The chalk test only highlights what is touching the surface across the face of the tire. Irrelevant info for off road.

When you drive off road, you air down for two primary reasons: To improve ride quality (softer tire action), as well as added traction or floatation. The tire can then wrap around hard objects, or spread the vehicle weight out over a longer ground contact patch in soft ground.

If you will, plz detail how you go about finding the optimal PSI for off road using that chalk method. I am seriously curious.

 

I'm still baffled at what information this placard is telling you that refers to airing down for off road, just as the OP asked about.

 

If you're worried about scraping that rock that might be 1/2" too high, maybe leave the truck in the garage.

When I built my skid plates, yes I absolutely lost some clearance. Did I start scraping them on every obstacle? No. You're over thinking that 1/2".

 

I think your post before this was the perfect capstone for your point: airing down reduces clearance, but you believe that airing down is much more critical than clearance loss. Got it, we don’t disagree. Any further discussion of the finer points, if you will, of this point, do no one any good. I’ll take my extra 1/2” of clearance on a trail where the extra traction isn’t necessary but the clearance is, because that’s what lets me take a stock truck out and off road on that particular trail. On another trail I may air way the heck down because the clearance isn’t an issue but the traction is, because of the specifics of the trail. On another trail, I won’t go because stock isn’t gonna cut it.

Now the OP has multiple perspectives to consider. The end.

 

Discussing the finer points is literally what this forum is all about...

As I and others have stated already, airing down isn't just about traction, and your perspective seems not to consider that.

The idea that the extra 1/2" clearance gives you any sort of actual advantage is likely in your head. The real world has too many variables for that to really matter. Driving a line 6" to the left or to the right will make more of a difference. Hell, even proper throttle/brake control can mean you aren't loading the suspension at the wrong time.

 

I’ve offroaded for over forty years and never chalked a tire. So there is that. Asking a question with so many variables makes it impossible to answer

My suggestion is air down until you get good traction. If you bust a bead, reseat it and air up a bit. Continue on and enjoy the day.

 

I thought this forum was about sharing observations of our experiences for the collective knowledge, rather than telling other people that they were imagining things, silly me.

I think we can go ahead and close what has become a circular conversation.

 

This is a an ever evolving world we live in currently giving us the ability to communicate at much much faster clips than we used to with smoke signals.

So, with that I say:. "Why not both?"

 

Thanks to all who have posted a response. Thumbs up.

Years ago I participated in parking lot slaloms in a sports car and used liquid shoe white to determine proper tire pressure regarding tire performance at the tire’s shoulder (can’t let low tire pressure allow too much shoulder wear/rollover). Understand the chalk test for actual tread surface. Does “painting” a SIDEWALL perhaps give clue to OFF-ROAD tire pressure? I realize it’s more of a TREAD shape than sidewall issue. Thought is painted shoe white on sidewall would crack/flake off to indicate something. Or not. Perhaps too many variables with terrain types.

For those suggesting going out with a club/group of experienced off-roaders, I totally agree. My distaste for Facebook and midweek days off hinder this slightly. Not impossible, simply more challenging.

Slowly gathering my recovery gear, tire inflation/repair equipment, etc. for the day of actual experience.

thanks again from the OP

 

reduced tire pressure is more important for personal comfort then vehicle traction.

If you are in a scenario where you need to absolutely optomize tire pressure for offroad use then you are a rock racer or some very skilled Baja racer.

For causal offroad use, just make sure it's not so much that the sidewall is rolling and rubbing the ground as your drive (nearly impossible) Usually 12psi is as low as most anyone goes without dedicated beadlock wheels. If you want to drive fast offroad then I suggest 18-20psi.

 

Mostly correct. Reduced tire pressure for loose/soft soil and snow plays a bigger part than for personal comfort.

The softer material wouldn't actually be uncomfortable in itself. The side effect of excessive axle/wheel hop trying to propel forward would make it uncomfortable.

Airing down in this situation solves both issues. Floatation and no wheel hop.

12psi is the lowest that I would run stock tires due to the amount of sidewall flex. 12psi with a stiffer sidewall rated tire is not the bottom for me. I ran 10psi in front and 7psi on the rear of my '85 22R Toyota XtraCab on 33" Buckshot Mudders with stock gears in the sand. Not enough HP to spin fast enough, so floatation was my friend.

 

Ha there's quite a few opinions here. Here's a video to help some folks get up to speed.

https://www.youtube.com/watch?v=5oKMD8iuAJY

In short, you can go pretty low as you can see. Personally I don't go below 15psi since there isn't much of a need for me to go beyond that. 20-25psi seems to be the sweet spot for airing up quickly

 

thanks for the link and info!

 

No problem. I do a good amount of driving on the beach slaying surf perch so I have a little experience.



I’d say 15psi will get you just about anywhere in the sand. Like, allows you to drive up 45deg dunes. As always, your tires make a big difference too

 

Guess I better return my geolandar g003s since they are shit for off-roading.

 

This is the right info. It's just math & physics - the engineering definition of traction is the amount of available force to be transferred between an object (tires, shoes, etc) and a surface (sand, dirt, snow, etc). Loose surface material has a much lower crushing pressure than something cohesive (like pavement) so the material below the tires fails before it can transmit force from the tires into the ground and allow you to move.

When you air down, you increase the surface area over which the weight of your vehicle is distributed. Force/area = pressure (or stress for you engineers out there). The same amt of force distributed over a larger area = less pressure on the surface material. Less pressure on the surface material means it's much easier for the material to stick together and provide the resistance for your tires to "push against" and allow you to move more efficiently over the surface.

The only time this isn't true is when you're driving on ice or other super slick, hard surfaces. Then it becomes a game of staying under the coefficient of friction and you want the force of the vehicle distributed over the smallest area possible. Think pizzacutter tires or ice skates.

 

Ice skates are designed to maintain friction on ice? I thought they were designed to glide. Friction comes in to play only when using the sharp edges to dig in perpendicular to the direction of travel for stopping, starting, and staying at speed.

 

I run my Falken Wildpeak MTs at 11psi. ALL the time, crawling.

17x9 wheels. 285/70R17 tires.