2500HD E-rated tire pressure question

[jocko]

Does anyone know why GM lists 60 psi front and 80 psi rear for E load rating tires on a 2001 2500HD? i.e. why the split? Tires get rotated (as in, rotated front to back, crossed, etc at mileage intervals, etc) so that implies deflating and inflating as tires move around to keep the tire pressures correct.

Have seen a few threads on here discussing proper inflation pressure for E load rating tires - folks seem to want to under-inflate them. As far as the door markings for pressure, it's the 60/80 split mentioned above. The tires just display 80 psi at max load (which, on non-E-rated tires usually meant something less than that number was normal - but from all I can tell/read/pick out of the manuals, 60 front/80 rear seems to be the actual required inflation at all times, loaded or unloaded). (These particular tires are LT24575R16, the original factory tires on the truck from 2001). But asking in more of a general nature, not specifically about these particular E load rating tires, more like any E tires.

Thanks all.

[82C10step]

Those pressures are for a loaded truck. I always run less in an unloaded truck. I back the rears down to 50-55. The fronts I leave alone. If you run the rears at 80 all the time it burns the center tread down quick.

[jocko]

Thanks 82C10step. So why 50-55 psi? That's kinda my point - I've heard many people say what pressure they think is about right for them (E load rated tires) -I'm looking for the documentation for what an unloaded K2500HD E load rating tire pressure should be if it differs from the max load pressures listed on the door. Have not found any - and everything I've read up on E tires indicates they should be run, even unloaded, at or near max pressure so the sidewalls don't flex/heat up. Discussion specific to these heavy duty E rated tires.

On other trucks I've owned (that didn't have E load rating tires), there was a max loaded pressure and also an unloaded pressure documented.

[82C10step]

I've always just watched tire wear. If you run 80 in the rear you can see the center of the tire wearing quicker. If your too low in the front it wears the outside edges and tends to wander.

[jocko]

On most tires, I agree, 80 psi will definitely wear the center out first - but I'm only talking about HD E-rated tires. If I'm not mistaken - the door label is COLD TIRE PRESSURE, not max load. Max Load is only listed on the tire itself. Everything I've ever read says to inflate to the door label (again, still talking about original tires here). For instance, my 2001 1500 label says cold tire pressure is 50 psi, and that's what I inflate them to - even though the aftermarket tires are rated at much higher psi). And wear has always been very even, no bad patterns in 270k miles yet. This new-to-me 01 2500HD is the first truck I've owned that came with E tires from the factory, so was surprised to see 60/80 psi f/r on there (once I found my glasses when I got home...). I took a wag and drove the truck home at 50 psi all around (because I didn't have my glasses with me and couldn't read the dang label or tire..) - but the sidewalls were pretty saggy and they still looked low. Since I didn't have my glasses, I didn't want to over-inflate them because they were the original tires, about 18 years old. Anyway, there I go. Everything written says inflate to the label pressure, even when the topic has nothing to do with max loaded weight. I'd rather inflate to the correct pressure in the first place than to correct a wear pattern after the fact - that's why I'm asking about this (and because I want to make these old tires last as long as possible, they're old but have no dry rot and lots of tread). For E rated tires, specifically, most of the stuff I've read seems to indicated that E rated tires need that much pressure (60-80) in general to keep the sidewall fully inflated and to avoid heating up too much. And that is what's on the door label.

[jocko]

Ok, after a little more digging - here's how the owner's manual actually states it regarding the "Cold Tire Pressure" annotation on the door label:

"The label shows size of your original tires and the inflation pressures "needed to obtain" gross weight capacity of your vehicle" - as has been previously mentioned.

So, the same question remains - is there a manufacturer's recommended inflation pressure (if not the pressure on the doors) for a truck operating well below GVWR, i.e. empty? This seems to be simple, yet, it's so vaguely explained (to my pea brain - it leaves an unanswered question, although I never really thought about it when I ran around in 1/2 ton trucks, just inflated to the door label and called it a day, always worked, have always had even tire wear). But the 60 front/80 rear note on the 2500HD's door label got my attn, had not seen psi ratings that high on a door label before ) The fact that I can't find any reduced pressure mentioned anywhere leads me to believe the pressure on the door label is the correct answer for all scenarios, loaded or unloaded. And I've always done it this way on all my vehicles - but 82c10step, you are certainly not the first person I've heard state that they run at a lower pressure than the door label calls for when not operating at max GVWR. Many folks say the same thing.

So, does anyone have some documentation that says to run below the door label cold pressures when not at max GVWR? Or documentation that says to always run them at that door label pressure? As written, I'm interpreting the owner's manual to mean run them at the door label pressure all the time - and that that is the only way to support max GVWR. No mention of anything different when below max GVWR seems to imply no changes from these numbers, but it can leave an unanswered question floating around out there about below max GVWR ops.

[hatzie]

I usually run them at 45-50PSI and ramp up the rears if I load the bed or tow big-n-heavy.

The treadwear stays pretty even across load range E tires at that pressure.

If you're running Passenger tires it's a different ballgame.

[jocko]

Copy Hatzie, thanks very much.

[truckdude239]

I normal recomend to my customer if they are not hauling 60psi seems to be best wear

[jocko]

Thanks David

[Brentwe]

If you are wanting pressures for tires on an unloaded vehicle, go to the tire manufacturers inflation load chart, as noted, vehicle recommended pressure is for gvw of the vehicle. Max pressure on tire is for tires max rated load, may or ,may not be same as vehicle.
3500 Ram truck 80 psi when I'm hauling, rears are at 45 once the rv is parked for winter, that is more than enough pressure to carry an empty truck box.
Hope this helps.

[jocko]

Thank you!

[aggie91]

I have an 06 2500HD Duramax. I run 60 psi all around and the tire wear is real even. I sometimes air up the rears to 80 if I am hauling a really heavy trailer or load...but a lot of time I don't...

[jocko]

Thanks Karl!

[MJN]

FWIW- my Yukon XL 2500 is the same way, door pillar sticker says 50psi front, 80 psi rear. I typically run 50psi front and 65/70psi rear, no issues with uneven wear, they get rotated every 6000 miles and I adjust the pressure accordingly. I don't always pull a trailer and don't bother with changing pressures but with the added weight of the Yukon vs an empty pickup the ride is more than comfortable. Plus I seem to get pretty good mileage compared to other 6.0L's out there.

[greasemonkey]

When I worked at a tire shop years ago, most owners would run about 65 front/ 55 rear or 60/50 depending on the configuration of the truck.
My brother in law bought a 2500 Ram that has 80/80 on the door placard. He tried to bump them down due to not towing/hauling and set off the TPMS around 70 psi. He tried to get it reprogrammed and the dealer told him due to legal issues, they weren't allowed to. Apparently they had too many cases of people attempting to max out the GVW without raising the pressures to compensate, so Ram was forced to set the pressures to the max. Sacrifice tire wear for safety, I guess.

[jocko]

Thanks Guys, when unloaded, I'm gonna plan to run 55 front/70 rear (rather than the full 60/80 as marked on the placard) and check the wear/ride and see how it goes. Might bump it up to the full 60 recommended in the front since I've got the fat 8.1 up there. I really appreciate all the great input.