tire pressure

The E-load tires you now have only need little more pressure then the P-tires wich are B-load tires with pressure needed for the maximum load of 35 psi.

But when you search for the pressure advices, on same plate is mostly the Gross axle weight ratings ( GAWR) and GVWR ( V for Vehicle).
Then read from tires the maximum load ( googled and found 109 Loadindex wich is 1030kg/<>2260lbs a tire for P tire in 245/75R16) and check if it gives AT 80 psi on sidewall.
Then to make it complete give speedcode ( probably Q for up to 99m/h)

Then I will calculate the needed pressure for you with use of one of my made spreadsheets , In wich I use an even saver formula then the tire-makers use. Also with some reserve for towing.

I expect the outcome to be as low even as about 40 psi rear when towing. Front then can be even lower because GAWR front is mostly lower then rear and when towing front axle is lifted up a bit by the weight on the pin.

Good choice in gong from 'P' rated tires to 'LT' due to towing BUT
I see new rims in your future :B

I run 80# rear when towing because I am at MAX Load Rating on rear tires and need the max air pressure.
I air down to 55# rear cause that is what I need in tires when not towing

Fronts stay at 55# cause weight doesn't change towing or not

BUT those air pressures are what give me good wear, traction & stopping power on my truck and set up. YMMV

If your truck came from the factory with P-rated tires there's a good chance the wheels were matched to the tires. They probably can't handle the higher pressure that you can put into the LT tires - you need to dismount a tire and look for the pressure rating of the wheel - usually stamped into the wheel on the inside.

john&bet wrote:
I lower the air pressure in my "E" tires on my 2500 to about 65 rear and 60 front when not towing. I up my front to 70 and rear to 80 when towing.

Pretty much the idea. When upgrading tires a fair amount, you want to be careful not to overpower your suspension when not hauling a load.

Lowering the pressure unloaded a bit allows harmony between tires, suspension, and road, yet still enhance performance when loaded.

Michelin should have a inflation/weight chart online. I saw one for my old 19.5's.

I run the same tires in a 265 size on my 3500.

60 front; 65 rear empty.

65 front; 80 rear when towing a 13.5K fiver.

That is what feels comfortable and is within the sidewall limit.

Do you know the maximum inflation rating for your wheels?

Until you weigh your truck with and without the travel trailer fully loaded as if you are going camping you should run at maximum pressure on the truck.
When you have weighed the truck you can then find the TIRE MANUFACTURERS chart that will give you the correct pressure for the tire based upon the weight.
What others run is immaterial to you because the weight is the important factor in determining proper inflation.
Tires inflated to max = no problem
Tire under inflated for weight = tire damage

There is no shortcut unless you just run at maximum inflation

I will check for a tire pressure label when I get home from work .. on the door I assume? Will that tell me different pressures for different weights or do I just do like JohnandBet is doing and use a standard 60/65 and 70/80 lbs ? the tire dealer let me drive away with 45lbs and I also found out I should have been given high pressure valve stems, which the didn't put on. Geepers!

What does the tire pressure label on your truck specify?