Looking for a quick and easy way to improve the off-road performance of your truck camper rig? Try airing down your tires. Sure, you can spend big bucks on flashy, double barrel King Shocks, on locking ARB differentials, and on Banks Engineering air intake and exhaust upgrades, but why spend the money when you don’t have to? This article provides valuable off-road tips on how to air down your truck camper tires and which tire pressures to use when off-roading.
Why Air Down?
How does airing down your tires improve off-road performance? Why is it so effective? First and foremost, airing down improves traction by increasing the contact area of the tire and allows your tires to deform around uneven obstacles thus maximizing grip. Second, tires that have been aired down are easier on your truck’s steering and suspension components. Third, airing down reduces the spring rate of your truck’s suspension system, meaning your tires will absorb impacts more than your springs and shocks. This reduced spring rate results in a softer, much more enjoyable ride. Nowhere were these improvements more apparent than on a recent run we made on Sedona Arizona’s Schnebly Hill Road in our Ram 3500 and Northstar Laredo truck camper.
Schnebly Hill Road (FR-153) isn’t particularly long, it’s only 12 miles in length, but parts of the drive are rough and uneven. The mountain road, which climbs nearly 2,000 feet, really isn’t maintained anymore with parts of it rocky, deeply rutted and pitted. We typically don’t bother airing down our Cooper Discoverer AT3-XLT all-terrain (AT) tires for short runs like Schnebly Hill Road, but after driving on the rough and rocky road for a couple of miles we had enough. On a recent run on Moab’s White Rim Trail we had experimented with a combination of 35 psi front and 40 psi rear and those pressures worked well for us, so we decided to try those same pressures here. We immediately noticed a big difference in how well the truck handled after airing down. We still had to take it slow over the rough and rocky surfaces, but the jarring was much more tolerable.
In contrast with hard and rocky surfaces, the soft sand found in places like the Imperial Sand Dunes and the Virginia Capes provides its own set of unique challenges for the overlander. Sure, it’s smoother and easier on your dental work, but you can also lose traction if you don’t use proper tires pressures. In soft sand, we recommend using pressures of either 20 psi front and 25 psi rear or 25 psi front and 30 psi rear. Other truck camper owners have used pressures as low as 15 psi front and 20 psi rear in the really soft stuff, but we’ve never gone that low. The bottom line is that you have to experiment with the sand you’re driving on.
While on the subject, here are a few tips for driving in sand. Avoid making sharp turns. Doing so with low pressures can peel the tires from off the rims. You’ll also want to avoid sudden stops and fast take offs since these can result in burying your tires. Finally, if you do a lot off-roading, you may want to consider buying a set of mud-terrain (MT) tires like the Cooper Discoverer STT Pro. Featuring aggressive tread patterns, MT tires offer outstanding traction on most surfaces except soft sand. When it comes to tires, contact with the surface is key. The more tire surface in contact with the sand, the better, just be careful that you don’t air down too much to the point where you lose the bead.
Recommended Tire Pressures
What pressures for 10 ply SRW load range E (max 80 psi) tires does Truck Camper Adventure recommend?
- Firm dirt surfaces/Gravel – 50 psi front/55 psi rear
- Uneven surfaces – 40 psi front/45 psi rear
- Rough and rocky surfaces – 35 psi front/40 psi rear
- Sand – 25 psi front/30 psi rear
- Soft deep sand – 20 psi front/25 psi rear
Note: The same pressures apply for both SRW and DRW tires in sand. However, when airing down dual rear wheel tires, care must be taken not to air them down too much where the tires start rubbing.
Deflating Devices
What devices can you use to air down our tires? You can do it the old-fashioned way with the tip of a screw driver, but that takes more time. A much quicker way is to use a set of Staun heavy duty tire deflators. These high-quality tire deflators makes the task of airing down quick and easy. The deflators come factory preset at 35 psi, so if you want a different setting you need to manually set them yourself. Setting them up isn’t that difficult, though. All you need to do is air down a tire to the pressure that you want, then install the deflator and adjust it until air is released. It’s that simple.
If you don’t find this method of deflating your tires appealing, then you might want to check out the ARB E-Z tire deflator. This pretty cool device rapidly deflates your tires, one at a time, by removing the tire’s valve stem core. Air is manually released using the easy to operate sliding valve. The benefit of going this route is that it allows you to quickly air down your tires to individual precise levels using the included tire pressure gauge. The price for the ARB E-Z tire deflator is also half the price of the Staun deflators.
Going down the Shaffer Switchbacks on the White Rim Trail. (N. Sturgeon)
The VIAIR 450P Portable Air Compressor
Airing up with the VIAIR 450P after a three-day run on the White Rim Trail.
Airing up with the VIAIR 450P.Airing Up
Of course, after airing down your tires after a day on the trail, you’ll need an efficient way to air them back up before hitting the pavement. For this job, we use the VIAIR 450P air portable compressor. This lightweight unit gets its power by connecting directly to your truck’s 12 volt battery. The VIAIR 450P generates an operating pressure of 150 psi for up to 40 minutes before it automatically shuts off for a period of time to cool. It delivers 1.80 CFM free flow at 0 psi while the maximum current draw is 20 amps. The VIAIR 450P comes with its own soft carrying bag, and includes everything you need to air up your tires, including a 25 foot coiled extension hose with quick connect coupler, a gas station style inflation gun with a 200 psi pressure gauge, and an 8-foot-long power cable.
Inflating each Cooper Discoverer AT-XLT tire from 40 to 80 psi takes about eight to 10 minutes, which is a little long, but it’s still within the 40 minute, 100 percent duty cycle spec. You can purchase the VIAIR 450P on Amazon.com for $297.00. Expensive? Yes, but like we always say, you get what you pay for. All things considered, this is a good price for a quality air compressor, especially when you factor in free shipping using Amazon.com Prime.
Great Article, answered some of the questions I had. BUT with a payload of 4,200kg would it be unwise to run a”D” rated tire 50 psi max over “E” rated 80 psi max.
thanks, J
‘Load Range’ (LR) is the measure of a tire’s capacity to act as a pressure vessel (hold air pressure). This is not the same as the Load Index (LI) which is the tire’s capacity to carry weight.
LR and LI are weakly related in that the maximum load capacity will also be achieved at the maximum tire pressure. A higher LR does not cause a tire to have a higher LI.
A higher pressure/load range tire CAN and often do have a higher capacity (load index) but not always. For instance, a Load Index 123 tires exist in both Load Range D and E. Both tires can carry the same load BUT the load range D can do it at a lower pressure WHICH IS AN ADVANTAGE for off road travel. Because they have the same load capacity at different pressures, the Load Range D tire MUST have a larger contact patch (usually wider) than the Load Range E tire.
While most truck owners THINK a higher load range tire is a benefit, it is NOT. If you are intending to operate on low-bearing strength surfaces such as wet soil or sand, you are better off with a tire that can still have the appropriate load capacity AT A LOWER tire pressure.
Steve, thanks for your three comments. Most helpful. Very clear once I grasped the force/area had to be equal to the surface “strength” i.e. what force/area it could withstand. I like the guideline about walking and your feet appling about 15 PSI. I went to White Pockets early this year with pretty soft sand. I sank into it with my feet which is why 20psi in my e-series tires struggled. I didn’t get stuck, by my MPG went way down.
I’m driving a Ram 3500 DRW crew cab with a Host Mammoth in the bed (around 6k payload). What would you suggest for psi in the 6 tires when driving in soft sand. I’m obviously concerned with losing a bead. I have years of experience beach driving but none with a DRW nor with that payload
The same pressures apply, just be careful that the rear dual tires don’t rub and you don’t lose the bead.
The appropriate tire pressure is the one that is equal or less than the bearing pressure of the surface on which you want to drive. Your vehicle applies the same PSI in your tires onto the surface over which you are driving.
If your tires have 30psi in them and you have and have 6000lbs on the axle (1500lbs/tire) your tire (on firm ground with more than 30 psi bearing capacity) will flatten out till it has a contact patch of 50sqin. If your tires are 10″ wide, the flat contact patch will be 5″ long.
If you drive on a surface that can only support 20psi with 30 psi, your tire cannot create a large contact patch because the internal pressure will not allow it. What will happen instead is that your tire will sink INTO the surface till the tire comes in contact with more soil till the area in contact with the deformed surface is equal to is soil’s bearing pressure. Your 50sqin (flat) contact patch will become a 75sqin (consisting of 50sqin on the bottom and 25sqin curved patch in front). The additional 25sqin on a 10in wide tire is a 2.5″ ‘ramp’ that is realistically an inch deep rut. You will sink into the surface till this area is created. This means you will always be creating ruts and essentially driving ‘uphill’ as if trying to climb out.
‘Soft sand’ (dry) probably has a bearing pressure of 10psi or less meaning if your tire pressure is much more, you will create very deep ruts, possibly too deep to climb out of (aka ‘get stuck’). Using the knowledge that your foot applies 15psi, walk on the surface which you want to drive and evaluate the result. If your foot sinks significantly, assess the likelihood of your vehicle tires ability to drop to pressures well below 15psi. Soft sand driving pressures are typically below 10psi. Your 6000lb load at 10psi will need 600sqin to remain stable. That’s 150sqin per tire. Assuming your tires are 10″ wide, that means the flat area front to back would be 15″ long. I don’t think you can get your tire to be a 15″ long flat on the bottom unless it were completely flat. Do you think you could drive that way? for far? what risk of losing a bead are you will to take? If you can’t go that low, you should not drive on it.
I have Nitto ridge grappler 305x65r18 tires. I spoke with Nitto tech,He gave me 40lbs. front 60lbs rear for my truck weight. He said do not air down,at lower pressures damage will occur lower. Call Nitto and ask.
That’s true when driving at high speed. But no damage will occur if you drive at low speeds like we’re doing when we drive off-road. Generating heat is the problem and if you’re driving at low speeds you won’t generate much if at all.
Ditto Mike’s comment. Load Inflation (pressure) Tables specify minimum pressures for a given load ONLY AT HIGHWAY SPEED where maximum tire flexing produces maximum heat. You can lower your tire pressure as low as you want to suit the surface on which you want to drive as long as you also observe the ‘max road speed = 2 x tire pressure’, rule of thumb. For example, 15psi = 30MPH max speed.
I have my own corollary to this rule and that has to do with time. It takes time to build up heat so if I’m running my Jeep at 10-12 psi, which I commonly do off road and experience no significant heating, I will run it at those pressures up to 55MPH on the highway for up to 20 minutes (applying the 2x rule liberally but this time with TIME). I have checked and they do get warm but not that much. I also run it for longer if the weather is cool. This is often used when I am connecting from my campsite to or from an off-road destination over multiple trips/days.
The points at which low tire pressure can become a concern are; 1) Hitting a point object on the irregular road surface that causes the tire to deflect completely until the inner surface of tire comes into contact with the wheel, 2) if the tire are so deflated the inside surfaces rub on each other (this is where the side bulge folds onto itself such as when you’re tire is completely flat) or 3) if hard steering is required to negotiate the terrain, potentially causing the bead to come off the wheel. Avoid these and you can run at any pressure for any duration without tire damage.
Thanks for all the info you put up for all to see. I have a question on this article. I just got a 2016 F-150 Fx4 with 20 inch wheels. I tow a Forest River a-frame pop up trailer, 3,000 lbs loaded. Should I lower my tire pressure on washboard roads to make it smoother. And should I also lower pressure on the trailer as well? Thanks for helping all.
That is up to you. It depends on how “bad” the road is. If it’s pretty bad, I would air down. I wouldn’t worry about your trailer. Since everything is stowed away.
Good article next time I’m at Anza Borrego I will try the 25 front,30 rear with my LT265-70-17 ten ply