tire pressure question

Gotta factor in the tires aspect ratio...

Lower aspect ratio will have shorter sidewall height...therefore stiffer
than higher aspect ratio of the same class tire ('P' vs 'LT') and
section width

So if he gets 20's, they will have a much lower aspect ratio than
my 16's

PS...some 'LT' class tires has a max pressure of 35PSI...I have a
set on my Silverado

New information I found out later, after I made the original post about the sway problem.

(That my friend may have a newer model F250 in his future).
this should solve his tire sway problem as the F250 should come std with E rated tires.

Good for him, newer truck, most all of us would like to have a newer bigger truck, in our future.

Problem should be solved.

Thanks for your input,

If the rimms are rated for the higher loadrange , you can find on the inside. The given pressure is cold pressure and rising pressure by rising temperature in tire is taken into account.
So you have to take it from the car to read it .
Mayby the spare is the same rimm and then you can more easyly take that .

The conclusion I took is that LT tires are more stable because they need higher pressure to give the tire the same deflection. this higher pressure makes the sidewalls stiffer so lesser sway
If you give the P-tire the same pressure, the deflection gets less so more bumping, and more nervous driving.

P tires are allowed to bare the maximum load up to max speed of tire ( or if lower 99m/h) AT 35 psi cold ( USA system) , the 44 psi is the maximum allowed cold pressure , and is used for higher speed and camber angle above 2 degrees, but can be used for road handling and expected overload ( for that the tire makers dont support that higher load , but laws of nature do).

Unless you find Extraload/reinforced/XL on sidewall then its and XL and they need 42 psi for the same maximum load and conditions as given above.

Thanks guys,
I am sure his tires are P rated tires
if he is at 40 psi, then 44 psi would be his max.

his tires look almost new, so replacing them may not be a option at this time.
guess he will just have to deal with some sway until he changes tires.

thanks,

will his wheels be rated for the higher pressure of LT tires??????

Look on the sidewall of the tire and it will tell you the max pressure. I'm thinking it's probably 44 psi.

He needs to check whether he has P or LT tires, and the max inflation should be on the tires. If he has P tires, he needs to replace them....I did that on my Tundra and it made a big difference towing. With most LT tires, the max inflation will be 80 lbs.

Sounds like your truck has LT tires and your buddy has P tires. Big difference in sidewall stiffness. I had a Tacoma with P tires and towed a TT. I installed a set of LT tires and noticed a big difference in handling and stability when towing. Might be more than a tire pressure issue.