Tow Vehicle Tire Pressure

[Airdale]

Originally Posted by Seachaser186

The reason I asked the question, there are those who are saying to inflate to max psi for towing. If you drive the psi will exceed the max. That is why I don't inflate to max to allow room for expansion.

Ever heard of thermal equilibrium? Tire engineers factor it in when designing, building and setting tire inflation pressures.

[Airdale]

Originally Posted by Ltynman

The 35 psi is on the door sticker.

Those are passenger tires. The maximum load capacity on their sidewalls has already been reduced by the vehicle manufacturer. Use the chart pressure for 35 PSI and divide it by 1.1 to get the actual load capacity.

Your truck's owner's manual should have increased PSI pressures for towing condition, if warranted. If not, use what the placard says. Those values are good for up to and including the truck's GVWR.

[Timtation]

Originally Posted by Chuckinca

The door plate on my Ram 3500 states max rear tire pressure when loaded is 75 PSI and 45 PSI with light load.

What is the major advantage in running the rear tires at a much lower pressure?

.

lower pressure = smoother ride. To get the smoother ride the tire flexes to absorb road variation. More flex=>temperature to the sidewall and air pressure. Increase the load and flexure increases as does temperature hence the increased recommended pressure to reduce flexure of the sidewall.
Two ways to check for correct pressure:
1. Is the tread wear equal across the tire?
2. Is the temperature equal across the tire?
Of course the first is a long term (5000miles?) evaluation while the second can be checked after perhaps as little as 50 miles of highway travel.
WWYP

[Airdale]

Originally Posted by Seachaser186

They are 275/65R/18 116T

For usage on a pick-up truck that tire has a load capacity of 2505# at 44 PSI.

Ref: FMVSS 571.110, paragraph S4.2.2.2; When passenger car tires are installed on an MPV, truck, bus, or trailer, each tire's load rating is reduced by dividing it by 1.10 before determining, the sum of the maximum load ratings of the tires fitted to an axle.

[Seachaser186]

Even with the de-rating of the tires at 2765 lbs. you would still exceed GVWR before overloading tires. Next set will be LT's but meanwhile I just add 10 psi to stiffen sidewalls for towing. Normal 36 psi, towing 46 psi, max 54 psi. I am actually doing it towing 7K and it works fine for me.

[KingFisher]

I never knew this stuff was so complicated. I've always just inflated my truck and trailer tires to the max cold pressure listed.

Windjammer 80 pounds. Sunset Trail 50 pounds.

Last truck 35 pounds all around.

This truck 60 pounds front, 75 pounds rear.

Don't know why I'd sacrifice mpg by underinflating for some perceived better ride quality.

[Chuckinca]

Thanks for the comments on lowering rear tire pressure when not having heavy load.

.

[325BH]

Originally Posted by Seachaser186

Can somebody answer this question? If you inflate to max psi for towing the psi will increase when the tires heat up. Is the max psi for a cold tire?

It says on the side-wall right next to the max psi: "cold"

[Seachaser186]

Thanks, I understand it means cold. I just looked at 2 sets of tires and either of them mentioned cold on the sidewall. Both of these are popular P-rated brands. I guess that's why people ask questions.

[mxdad]

I run 35 in the front and 40 in the rear when towing (6800-7000) loaded. Recommended is 35 all around. On hot days, the rear will go up to 45, but side to side motion is reduced. Tire sizes are 285/45/22 ( I think).