It's funny, all over the place this seems like common knowledge (filling P-rated tires to the sidewall max while loaded or towing), but I'd NEVER heard of it until last night! People claim that it makes a pretty dramatic difference in towing performance. If it makes any difference at all, I'll be tickled pink! I still have a lot of life on my P-rated tires, so E's are not on the table for a while so I want to get as much out of my P's as I can.
Also, from what I read, tire engineers do take increased pressure due to temperature into account when figuring sidewall max pressures. So I don't feel bad going with the max pressure on the sidewall, though I think I'm going to back off just a little.
To be clear, increasing to max pressure in a P-rated tire does not increase load capacity over that stated at the recommended pressure (usually 35 PSI), it simply adds stability to the tire under higher loads (allegedly).
I'm going to try it next time I have the trailer attached in a couple weeks and see how it goes.
2014 Jay Flight 28 BHBE
2015 RAM 2500 6.4L HEMI, Tradesman 4x4, 3.73
Blue Ox SwayPro (BXW 1503)
Upgraded from an REI internal frame backpack and a Eureka 1/2 dome tent!