I recently purchased a 2020 F150 screw 4x4 with the 5.0. The oem tires are P Metric Michelin Primacies 275/65/18. I am going to change to E load tires in the same size for towing a TT that fully loaded will weigh about 5500 pounds. My available payload is 1903 pounds. My front GAWR is 3450 pounds and my rear GAWR is 3800 pounds. According to load charts an E load tire should carry 1940 pounds at 35 psi and 1940 multiplied by 2 would equal 3880 pounds per axle and would exceed the GAWR of my my front and rear axle. My question based on this math is couldn't I run 35-38 psi in all tires whether towing or not and be within limits of my vehicle and maintain a comfortable ride when not towing and a safe comfort margin when towing without airing them up? Also would I get good tread wear leaving the pressures between 35-38 psi whether towing or not? Or should I just stick with the oem tires since I'm only towing 5500 pounds? I was only considering E tires for better sidewall stability when towing. Sorry if I'm missing something, Im just trying to get up to speed.
Thanks!

 

E rated tires should be between 50 to 60 when unloaded and up to 80 psi to the max.

 

Not sure about that, but you may have to trial and error on that. I keep a two gallon air compressor in the bed when towing, and I plan to run 60 to 65psi when towing, 44ish psi not towing.

With such a light trailer, you may not see much of a difference between the two tires with that pressure.

 

If they're on a 3/4 ton truck with an unloaded curb weight of 7000-7500 lbs and a GVWR of 10,000-14,000 lbs yea. The wheels on a 1/2 ton truck aren't even rated for over 65 PSI in them.

Short answer is you'll be fine at about the same PSI listed on the drivers door for the P rated tires that came on your truck. Even loaded heavy you probably don't need over 45 PSI. You'll have to experiment with PSI for best ride.

I like to run my tires a little hard anyway. Even with P series tires I'd run them closer to 40 PSI. I never knew when I might need to load the truck and it is easier to just keep more air in them than have to air up and down as cargo weight changes. I get 1-2 mpg better too. I keep the E rated tires on my Tacoma at around 35 PSI and about 40-45 PSI on my F150. I get 50,000-60,000 miles out of a set of tires and they ride just fine. At that PSI will carry more weight than either truck is rated for.

That said, you don't NEED E rated tires for your intended purpose. I prefer them for the type of driving I do off road or on rough roads. The tougher E rated tires will hold up to harsher use. If you air up the P series tires to near max on the sidewall, (usually about 44 PSI) when towing I think you'll be fine.

 

My Goodyear P metric tires get slippery at highway speeds when towing 5500 lbs. Most noticeable in a gusty cross wind or when being passed by a larger vehicle. I run them at 50 psi. However, it's not so bad that I'm ready to dish out the extra change to replace otherwise perfect tires.

My plan is to upgrade my tires once these are worn out. At a minimum I'll go with light truck tires, at a max E rates tires.

 

Although I have not yet towed with my F150, I towed plenty with my YukonXL with P tires and a similar trailer as yours (maybe 5.8k loaded). My P tires were set at 35 psi everyday, and ran them at 41 cold when towing, never an issue. Certainly not enough to warrant going to tougher riding tires all the time. I plan (and suggest to you), that you give it a try before you make expensive changes. I will agree, the better sidewalls, yada yada, but not towing, that's a stiffer ride. All this said, keep us posted

 

I'm positive on that, that's what my door sticker says. 2013 f150 HDDP.

 

I run E tires all summer, empty 44 rear, 46 front. Trailering 62 rear, 58 front. Great wear over the past 4 years