Full size rigs-Airing down

[Ducky's Dad]

Since OP has a new Power Wagon and has mentioned getting new wheels, I'll add this caution: The PW factory wheels have an internal lip that is there to keep the beads seated when running at low pressures off road. If you go with aftermarket wheels you will lose that lip because very, very few other wheels have that feature. An alternative is to use Hummer H2 wheels with the centers bored to fit the larger PW hubs. This gives you 1/2" additional rim width and moves the interior of the rim 1/4" further away from the control arms, and retains GM's version of the bead retention feature. The PW pics you posted show a wheel that is different from mine, so check your specs.

 

[twodollars]

I had 37s on h2 aluminum wheels on a 88 2500 diesel burb. Load range e, used 15 psi in the sand dunes with zero issues.

 

[IdaSHO]

If you are running E rated tires they shouldn't be driven on the blacktop lower than 45 psi. The low pressure causes them to heat up and eventually come apart. Ive learned this lesson...........twice now:yikes: Both times it required body work. Airing them down doesn't help much BTW due to the stiff sidewall construction.

There is no such hard-fast rule.

Consult an inflation table to find you answer.


FYI, I run less than 45 PSI often, on the blacktop, with zero issues.
So long as you are not overloading the tire based upon an inflation table, you are good to go.

There is even more margin to play with in cold temps.
Our winter travels, even loaded down heavy with the camper and weeks worth of gear and supplier, I run at considerably lower temps than I do during summer.

 

[aaen]

Well whatever you decide to air down to. No agressive maneouvers or you will be reseating the bead. On our larger work trucks we constantly fight with the tyre shops whom jack the pressures up to the max inflation for the tyre, they do it kn my tacoma. Nothing like an erated tyre at65psi in a taco. She sure is skittish on the road. One would think they woukd be experts at this, nope.

Anyways becareful offroading with the large trucks, learn to reseat the beads and most importantly have fun!

 

[CrazyDrei]

I run 37x12.5" on 17x8" rims, on the street I run 50PSI for daily driving and air down to 20PSI for off pavement. Get a set of tire deflators for $10 shipped on eBay, they are great once you take the time to set them up correctly.

I do not drive hard or super aggressive on the road or off. Usually drive home on the 20PSI tires with no problems as long as I stay below 60mph.

There are a lot of variables involved in the best tire pressure such as altitude and temperature. Start at 30psi and drop it by 5psi every time you do the same trail again until you get the ride quality that is best for you and stick with it.

I have deflated my tires to 20psi at 8,500ft and 30 degrees outside temperature for playing around a snow covered trail, then drove down to 2,000ft and 85 degrees outside temp to play on the dunes , drive home felt a little softer then usual, and following morning when I checked my pressure it read 5-8psi in all tires prior to inflating.

 

[TommyG]

I have 37x12.50s on the factory wheels on my Power Wagon and go down to 20 for regular trail runs. I have gone into the teens for deep, soft sand with no issues.

 

[Tex68w]

Do the wheels on the 2017-18 Power Wagons have this internal lip someone mentioned on the older wheels?

 

[arveetek]

If you are running E rated tires they shouldn't be driven on the blacktop lower than 45 psi. The low pressure causes them to heat up and eventually come apart. Ive learned this lesson...........twice now:yikes: Both times it required body work. Airing them down doesn't help much BTW due to the stiff sidewall construction.

I run my E rated BFG K02's at 42 psi on the street, and around 18 psi off-road. This is on a 6K (estimated) 2 door Tahoe diesel. I did the same with my old E rated Kendas. 50K miles combined on both sets so far with no issues. Heavier rigs will cause more tire deflection which will cause more heat build up I'm sure.

Casey

 

[marshal]

Do the wheels on the 2017-18 Power Wagons have this internal lip someone mentioned on the older wheels?

they have a safety ledge which helps with tire retention, but they're not a catch all. based on the weight of these vehicles, with 37's i would be hesitant to drop below 18PSI for aggressive conditions. E rated sidewalls are a pain in the *** to reseat.

Im sure others have gone lower with good results, but i'd rather stay on the safer side of bead loss without a beadlock

 

[1stDeuce]

If you're not running too wide a wheel, re-seating a tire is NOT tough at all, since the bead will naturally push out and seal fairly well against the rim, allowing you to easily air it up.
In my experience, it is also fairly difficult to de-bead a tire if your wheels are not too wide. I've done plenty of offroading at very low pressures on all sorts of tire sizes. I have yet to knock a tire off the bead. In fact, the only tires i've seen come off the bead were 16.5's

The whole fear of un-seating beads came about mostly because of the old 16.5" rim size, which had no such safety bead, and had a tapered beat seat area that required almost no force to dislodge if the air was let out of the tire. (You can easily knock a deflated 16.5 off the seat with your foot...) With 16.5's, even mild side loading could un-seat the bead at low pressures. That design has long ago become a thing of the past.

Tire pressure is best determined by experience, not by armchair warriors trying to make absolute limits like "never run less than 45psi in a LR E tire". Honestly, I know it's well intentioned, but poor advice at best, since the LR E ties on my TJ NEVER have more than 30 psi in them, and I have no fear of them blowing out. Tire pressure needed depends on how much weight the tire has on it, how fast you're going to go, and how far you're going to go fast. Perhaps what he meant to suggest was that you can't do 80mph for hours on a tire loaded to capacity but inflated to only 45psi... That would be good advice.

My rule of thumb is that I air down enough to get some sidewall flex offroad. How much flex depends on what I'm doing. On washboard or sand, you can go pretty low, and the lower you go, the better the ride and flotation. 20mph is not fast for low pressure unless you're cramming in a bunch of steering, or bashing into hard ruts with the side of the tire. On hard pack, I keep the pressure a bit higher so I can go faster without worry of wobbly handling. In big rocks, I run a bit more than for soft surfaces so I won't pinch a bead as easily.

On-road, the farther and faster you want to go, the less sidewall flex the tire will tolerate. I have no problem going a few miles down a paved road at really low pressure, but I'll keep the speed down.

Get out there and do some experimenting. You'll probably find that for an empty truck on 35's or 37's, you can easily drop to near 10 psi in the sand without worry. I find that the rear tires can usually go a bit lower than the fronts, since there's less weight on the tires.

 

[Ducky's Dad]

It's relatively easy to reseat a bead with a BIG ratchet strap. Just jack up that corner and wrap the strap around the circumference of the tire, then crank down the ratchet until the tire will take air. Not as dramatic as ether and a match, but it works.

 

[TommyG]

Do the wheels on the 2017-18 Power Wagons have this internal lip someone mentioned on the older wheels?

They still have the "bead lip" on the outside. I have torn a sidewall over the years but I have yet to pop a bead off in 20 years of running non-beadlock wheels on three different trucks. Not to say that it won't happen tomorrow so it is a good idea to be prepared to deal with it in the field.

 

[Tex68w]

They still have the "bead lip" on the outside.

Makes sense now why they are flat on the outer edge. I still think I'd prefer to run a 8.5-9" aftermarket wheel like the AEV Salta or something similar. I like the idea of beadlocks but I don't want to make that commitment until I see the necessity.

 

[TommyG]

Makes sense now why they are flat on the outer edge. I still think I'd prefer to run a 8.5-9" aftermarket wheel like the AEV Salta or something similar. I like the idea of beadlocks but I don't want to make that commitment until I see the necessity.

The AEV wheels have the same bead lip so you would retain that feature and get a little more width.

Don't sweat it too much. Read through the trip reports on the board here. You don't see tales of people on the side of the road or trial for hours with a popped bead. Not saying it never happens but it is not such a huge issue. If you pop one and can't get it back on you have a jack, lug wrench and spare on board to swap that puppy.

Set it up for what you are going to do with your truck. If you find out after some experience that you want/need beadlocks you can sell a good set of Ram wheels online in record time. I am seriously thinking of throwing a set of non-beadlock Method Race Wheels on this year (a little extra width like you mentioned) and running those until they aren't up to what I am throwing at them. I don't expect that I'll need to swap them anytime soon.

 

[Bayou Boy]

There's a lot of guys running regular Methods over on Cummins Forum and beating on them regularly with zero issues. If you have issues, they'll sell in a second too.