I think it's because the curb weight is more front heavy than back due to where the engine is located. This tire pressure difference between the front and the back should apply to other trucks too. Not sure if you'll have to change it when you're towing something.
The other 1500s (with passenger tires) don't have differences from front to back - 39psi on all 4s. I'm wondering about this too, because this last weekend I hauled home a half-full bed of wood and it felt a little squirrly at times, almost as if I was struggling to keep it straight.
Maybe we need to put the rears up to 55psi once there's a load in the bed, or a trailer hooked up? Or maybe my alignment is off.
I have always wondered why the PSI is the way it is. I work in the tire industry and am stumped. I thought it was air suspension related but the regular 1500s with air suspension have 39psi front and rear on the placard.
Just picked up a '16 Rebel that came with 45 PSI all the way around. So after the first cold night the front TPMS went off. I was surprised as it appears my dealer and many of you were to see 55 PSI as a setting for the front.
Is there a way to modify the TPMS settings? I was actually thinking about lowering the PSI before the warning came on.
Front should be 55psi on mine. Says it right in the manual and on the door frame. That gets better gas mileage than 45psi, so that's fine by me. Rear pressure is lower unless you have a big load. No issue there, either.
Manufacturers calculate the pressure settings for the load expected in the vehicle during normal use. They're calculated for best handling/mileage/load. I'd stick with the recommended settings. Mine were a bit low at the dealer, I asked, and they topped them off.
It might be worth the effort to look up a guide on tire pressures and loads, at least doing that you can have another frame of reference which may not be otherwise provided through RAM, just as long as it comes from the pros.
Agreed. Here are Toyo's recommendations on their tires for load/inflation. Note that on page 3 there is a box of bright red text:
WARNING! The maximum inflation pressure indicated on the sidewall of the tire may NOT be the recommended cold inflation pressure for your vehicle. Refer to your tire information placard or owner’s manual for the proper cold inflation pressure and the recommended tire size. The tire information placard (T.I.P.) can be found on the vehicle door edge, door jam, glove-box door, or inside of the trunk lid.
Note that it's only 55psi on the front end. Rear end is lower. I get a really nice ride out of mine at the recommended pressure, and good mileage. You can get a slightly softer ride on a softer tire, but your mileage suffers because of increased friction due to sidewall flex. Also, the tire sidewalls start to heat up, especially on long trips and higher (highway) speeds. The lower the pressure, the greater the effect. This heating degrades the sidewalls.
I've seen the results of a tire run at low pressure on the highway on a hot day. The sidewall actually smoked and blew out. Kid said he knew it was low, running 20 lbs instead of 35 recommended for his car. He didn't think it would hurt anything. He drove 2 hours on the highway at 70mph. Then the tire blew out and he sat on the side of the road until a tow truck came. (no spare) Meanwhile, the tire kept smoking for about 10 minutes and we got his wife and kids out of the car just in case. The sidewall of the tire, aside from being super hot to the touch, was crumbling apart on the inside and outside, as it sat there.
My 2009 Power Wagon with 285 70 17 BFG AT is recommended at 60 PSI all around. However, it has a "Light Load" switch that when activated lets me go down to about 45 PSI in the rear with out setting off the light. It's a necessity as a unloaded HD truck with 60 PSI in the rear tires will shake your fillings out. Unloaded I run the truck at about 55 front and 45 rear and that appears to be the best combination.
I really like the Power Wagons, real beasts. An old farmer friend of mine years ago had a Dodge WC62. It was tandem rear axle, 1.5 ton, while most of the WCs were 1/2 or 3/4 ton single rear axle. That thing went almost anywhere. The WC was the military truck from which the Power Wagon originally derived.
As far as your comments, it makes sense. The front end is always loaded by the engine. This is what we always did on the farm with the bigger trucks, softening them up in the rear when we didn't have loads.
I've been running all 4 at 52psi since airing up the rears for towing my camper 3 weeks ago. Seems to have taken out that fish-tailing feeling I was getting when they were set to 45 / 55. Not sure if it's coincidence (maybe something else is now broken in), but I'm gonna leave them that way.