I keep seeing the 55 front, 40 rear set up here and other forums, mostly for towing/empty there. I'm working on getting Forscan to adjust where the idiot light starts to scream at me. I'll probably bump back up to 60 for towing the stock trailer or the skid steer. Never had the thought of breaking a bead cross my mind until I saw your post. I don't plan on going down to single digits any time soon though! When I run the compressor I'll probably try to get it back up to about 50 ish before hitting pavement. Thanks for the info.I will agree with the others that for an empty truck, you can go about half the highway pressure for general offroading. Note that "highway pressure" is NOT what is posted on the door sticker, it's what's reasonable for highway travel for the load condition of the truck. I commonly run 55psi in the front and 45psi in the back of my truck when empty, and with the truck camper on the back (and usually at or slightly over GVWR) more like 60/70psi. When empty, I will have no problem dropping to ~30psi front and ~25psi in the rear for long distances on rocky or washboard roads. I've been down to ~15psi in the sand empty with no issues. With the camper, I drop the front to 30-35, and the rear to 35-40. Lower than that with the camper is for "emergency" situations.
FWIW, using ANY 12v comperssor to air up to 80psi is going to take a long time!! Fortunately, you almost never need 80psi in your tires, regardless of what the idiot light says... Even with my truck camper on the back, I run about 70psi max in my 255/80R17's, but if I air down, I only bother to air back up to about 50psi on electric. That gets me enough pressure to get up the road and use a better compressor to top off the tires. 10 or even 20 miles with 50psi in the tires even when you'd rather have 60 or 70 isn't going to kill them. Just keep it a little slower if it's really hot out.
Finally, your fears about pulling a tire off the bead are probably unfounded. When you air down, you should always drive a bit more carefully, but modern tires and wheels have pretty good resistance to debeading. I've been airing down for a LONG time, and I have NEVER pushed a tire off the rim. I've had my Jeep down a 4.5psi for a day at the dunes and had no issues, even with some more spirited than usual driving. I had a previous 3/4 ton truck down to ~10psi at the dunes to see how it did and was a little worried, but for nothing. In general, the lower you go, the slower you go and you'll be fine.
I like your test of the square stock under the tire. Might find some and play with that a little this weekend. The plug in compressor is a decent option for now. As I make adjustments and tweaks to my truck I'd like to find a truck mounted solution that I can link to one of my up fitter switches.My method of airing down to a safe starting point.
•Place a 1" square piece of steel under the center of your tire.
•Air down until both sides of the tire touch the ground.
This system provides a great safe starting point for airing down. I have used this system on vehicles from 4000 - 12000 lbs with great results.
As for compressor
If it plugs in its a POS
Avoid duty cycles
Amp draw is a direct relationship with performance. In most cases higher amperage higher performance.
Pictured below the rear of a 10700lbs truck
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