Tire pressures for all of these trucks vary based on tire size and vehicle capacity so the correct loaded pressure is on the yellow load sticker so you should start there and then make your adjustments.

 

Needed (cold) pressure is all about load on tire, and maximum speed used, wich you wont go over for even a minute.

Now for a normal used car, the loads and used speeds vary.

Determining the loads on tires is the most tricky part in it all, and your responibility.

I can make you a pressure/axleload list.
In that I give 90% of the axleload calculated with my determined extra tight formula, and for max speed 160kmph/99mph.
I determined this to give maximum reserve with still acceptable comfort and gripp.

Need for that next, can be read from sidewall.
1 maximum load or loadindex for single load ( or do you have dualload axle behind?)
2. Kind of tire to determine the referencepressure.
Yust yesterday saw your sise in E-load LT with loadindex 125/122 At 80 psi. But can also be that you have a P-tire AT 35 psi or EUR system AT 36 psi.

3. Speedcode, less important, because will be Q or higher, wich all have referencespeed of 160kmph/99mph.

For the reference- pressure and - speed, the tiremakers calculated the maxload, and there is a system to calculate for other speeds and load.

The carmaker nowadays only gives recomended pressure for GAWR's and maximum technical carspeed.Or they yust give referencepressure and dont calculate anymore.

Your GAWR rear is higher then front.
Or was the longbed dualload axle behind.
Only driver and a little load, more load on front axle then rear. So then needs higher pressure front then rear. In earlyer days, normal was calculated for axleload determined by the carmaker for 3 persons and a little load, and was usually front higher then rear.

Fully loaded and/or towing rear more weight then front so rear higher pressure. Exept for dualload axle rear, then that higher weight is devided over 4 instead of 2 tires.

 

My GM 2500 truck had tires with a max load capacity at 800 PSI and recommended 65 PSI at the front wheels and 80 PSI at the rear wheels. I ran with those pressures whether the truck had nothing in the bed or a 4,000 lb load. I have even wear across the tires at those pressures. I had looked at the tire manufacturers' various PSI charts and the numbers were garbage and I would have had underinflated tires that would have run hotter and had uneven tread wear.

I did add a Hellwig Big Wig rear sway bar and that helped the ride when the bed was empty with greatly reduced wheel hop, especially when hitting a bump or depression with one wheel while making a turn. No gain with a full load in the bed with the addition of the rear sway bar.

Run at the recommended tire pressures and then check the wear pattern after 2,000 miles. The old chalk test is worthless for multiple reasons so best to rely on actual tread wear.

 

Lots of pretty bad info in this post... Your tires will not wear better or worse... I can't imagine and empty truck running 80 psi in the rear, Why would you do that to yourself? manufacturers numbers were garbage? So you made up your own program? Or really didn't at all just defaulted to the factory full load ratings, which is completely unnecessary unless fully loaded, which is over 4000 lbs in the bed of my truck. You can measure (crudely) tire temps by the pressure rise which is easy to do with these accurate TPM systems. I can run HALF the pressure you do in the rear, get 50k from a set of tires. They are not running hot or wearing too quickly. I am not sure you can say what would have happened without having the experience...

You are likely one of the only people on the planet that believes a heavy rear swaybar improves the ride. It is well known that adding a bar like that degrades the ride over not having it at all. That is just an absolutely crazy claim but obviously one you believe.

The chalk test is a great way to go for the retentive. Tire manufacturers rated numbers are the way to go and correct pressures for the loads carried will ALWAYS net the best tire wear, rarely will max pressures net you good wear. No way you are going to see a treadwear pattern in the first 2000 miles unless you have serious alignment issues. My new set has 5000 miles on them and virtually no wear, even though they are being run well below the max load pressures.

Everybody gets their say on the internet but I think most of your response was incorrect and poor advice.

 

I recently scaled my truck (unladen, no passengers) and crossed those numbers with the tire manufactures PSI/Load numbers for the tires I have. Based on their chart I could do 35 psi rear (that's as low as their chart goes) and 45 front. At those pressures I could add 1k lbs to rear but only 100lb to the front before reaching tire load capacity. I currently run 55 all around but might try dropping the rear to 45, see how that goes.

What's interesting is that on my truck, 50 psi would exceed the Front GAWR, but it is 60 on sticker which exceeds that rating by almost 900 lbs. On the rear, 65 is the recommended psi and that only exceeds my Rear GAWR by 50 lbs.

 

My truck is a bit lighter than yours as a gasser. Recently I ran 48/40 for a while knowing I was still well within the safety limits. I upped it to 58/50 so I can leave my 600 lb ballast in the back and hook up the 900 lb snow plow to the front without adjusting. The ride is pretty much the same but I do have the weight in the back still. I think the sweet spot for most is likely around 45 rear for most empty SRW trucks and depending on engine choice, because there is a big weight difference, 50-60 in front.

I am running a 129 index tire rated for 4080 lbs each at 80. I like how the taller heavier rated tire can be run a little lower pressure. The lower pressure also increases the size of the contact patch which is good for traction. Rock hard tires on an empty truck are a bad choice for more than one reason.

 

Because in reaction #36 loadindex 129 was given AT 80 psi, I made a pressure/ loadcapacity list for it, as example for topicstarter. This with the system, I described in post #32.

So look acurately determined axleloads back in my list, and use the cold pressure in front of it, and still acceptable comfort and gripp.

This acurate determining of the axleloads in your situation is the most tricky part in it all, and your responcibility. So succes with that.


Then maximum reserve for things like :
1. Unequall weight R/L on the axle.
2. Inacurate reading of pressure scale, and pressure loss in time.
3. Incidental extra load.
4. To 10. Etcetera

So can be used for every tire with singleload LI 129/ 1850kg/4079lbs maxload AT 80 psi. And speedcode Q or higher, on singleload axle.
So dont add reserves or devide by 2 yourselfes, all done for you.

Cold psi/ 90% of axleloadcapacity
20 psi / 2088 lbs
22 psi / 2270 lbs/ lowest inEUR
24 psi / 2451 lbs
26 psi / 2632 lbs/ lowest in US
28 psi / 2812 lbs
30 psi / 2991 lbs
32 psi / 3170 lbs
34 psi / 3348 lbs
36 psi / 3526 lbs
38 psi / 3703 lbs
40 psi / 3880 lbs
42 psi / 4056 lbs
44 psi / 4232 lbs
46 psi / 4407 lbs
48 psi / 4582 lbs
50 psi / 4757 lbs
52 psi / 4931 lbs
54 psi / 5105 lbs
56 psi / 5279 lbs
58 psi / 5452 lbs
60 psi / 5625 lbs
62 psi / 5798 lbs
64 psi / 5971 lbs
66 psi / 6143 lbs
68 psi / 6315 lbs
70 psi / 6487 lbs
72 psi / 6658 lbs
74 psi / 6829 lbs
76 psi / 7000 lbs
78 psi / 7171 lbs
80 psi / 7342 lbs/ referencepressure
82 psi / 7512 lbs
84 psi / 7682 lbs
86 psi / 7852 lbs
88 psi / 8022 lbs
90 psi / 8191 lbs/ maxload x2 and sometimes given maximum allowed cold pressure.

Can be that other referencepressure is used for a E-load tire, have seen 75psi, 77psi, and 83psi, mostly on European version of LT is C- tyre, C for Comercial, so dont assume automatically 80 psi for E-load/ LRE/ 10 pr(Plyrated as is used in Europe).

 

Ran the truck through the Quick Lane at the local dealer today and got pretty good time, service and price. Not awesome, but good. I got the "Works" which includes rotating the 80 pound, 8 lug tires. I know the tires were rotated and the TPMS was trained to the new locations because my 65 psi tires are now on the front, and the 55 psi tires are on the rear.

I noted up thread some guys run higher in the front, especially with the diesel engine. I sort of thought it was like sitting in the bath tub with your back to the faucets, doesn't hurt but no real benefit. But I did like the way the truck rode and handled on the drive home. Since I won't get around to "fixing" it until next weekend I'll just drive it this way and see what I think. Might as well try it, might like it.

 

If you feel like playing with forscan lower your tpms 9 lbs off the door sticker amounts then drop the actual rear to 49 and front to 55. Scale it and make sure you are in a safety margin for your typical light uses. Should ride better.

Then try airing them up to 65 front and 70 rear.

If the light doesn’t come on when airing them up you are probably ok to leave it that way.

TPMS is supposed to work both ways. You could possibly experiment with lower settings.

That way you can air back up to the settings the factory sets. They are set that way so guys like me can drive off the lot and load it to max GAWR and not get a blow out and slam into a school bus full of children.

I would also recommend changing it back to stock or writing on the white sticker what you did upon selling the truck.

 

My trailer has Goodyear Endurance, and Goodyear publishes a nice table with the details of the best pressure to use for each size and load combination. That made me go to 50 psi instead than the 65 on the placard, which is WAY better for the longevity of the trailer.

I just installed a new set of Michelin Defenders on the truck and I was looking for a table like that, but I don’t seem to be able to find one. Does anyone know where to look?

 

I used this one when deciding on PSI for the stock size 20" Michelins on my truck. I'll see if I can find the source again.

 

I run 55F, 42-45R. OEM 20" wheels & tire size.

 

I would not use the Endurance list, they are calculated with a formula introduced in 1928 for diagonal tires, and lead to to high loadcapacity' s, certainly in the lower pressures. And did you take a reserve?

But if you give sizes and next from from both your Endurance ST and tires of towing vehicle, I will make you a safe list with build in reserves, so you only have to look back the acurately determined axleloads in it to get a safe pressure. This determining the axleloads is the most tricky part in it all, and your responcibility.

1. Maxload or loadindex
2. Kind of tire and loadrange/plyrating to determine the reference-pressure.
3. Speedcode, less important

See my post #37 for an example.
Also give howmany axles on TT, and if rear TV duall or singleload axle.

Did you experiënce loose screws on TT with the 65 psi?
To low pressure gives even more "comfort" for the TT.
But then driving fi 65mph one or more tires overheat, and little internal cracks are made, wich tear further in time, untill mayby only after 3 years that far, that tire blows, or treath seperates, and then the moment of overheating is long forgotten, and other things are blamed.
So this overheating is only allowed ZERO times in tire use.

My list gives maximum reserve, with still acceptable comfort and gripp, and no centrewear..

 

I was not going to use the Endurance table, different tires/size/application, no relation with the truck. I was just using that as example for what I want to do, in my opinion the tire manufacturer knows much more about the tire than the vehicle manufacturer which has to account for the worst case scenario and therefore the table from the manufacturer is way better as reference.

Any case I appreciate your offer. I have the truck in my signature with 275/65 R20, and as I said I just installed a new set of Michelin Defender LTX.

 

Is that 3750 lbs AT 80 psi, as I read from chart of a few posts before? Post #41.
But you based your 50 psi for your travel-trailer on the Endurance list, and so most likely no reserve and to low. So still usefull to give me the specifications, so I can make a list for your ST.