General rule for tire pressure?

goducks10 wrote:
You don't need to run the max if you're not towing the max. If you are only putting 600lbs on the rear of a 3/4 ton then 80 psi isn't necessary. If you're maxing out a 1/2 ton then yes air up to the tires max sidewall psi. I would go as far as to say always run max psi in a 1/2 ton when towing because most are near the upper end when hitched and loaded.

What are you towing and what's the load in the truck?

Towing a Keystone Cougar 29 BHS with an Expedition EL. Load in the truck 2 adults approx 315lbs. 3girls 1 boy- ages 10, 7, 4, 1....not sure on their weight! Minimal equipment.

acritzer wrote:

VintageRacer wrote:
The manufacturer of the vehicle or trailers maximum recommended pressure. The vehicle is on the door jamb sticker usually, often the trailer is on the data sticker with the VIN. In the absence of that information, the maximum pressure on the sidewall of the tire.

Brian

I understand that. Maybe I didn't ask clearly enough.
-Is it "generally" OK to run slightly under max pressure?
-If you're loaded light you should run "this much under max"

Etc. Simple guidelines that are good rules to follow.
I read a blurb somewhere that suggested not to inflate to max.

Maybe I don't understand guessing and pretending a rule of thumb for a set of equipment that I have no idea about is OK. If you don't know, you assume the maximum and set up for that. There is absolutely no downside to running the trailer tires at the sidewall maximum pressure, I've done that for thirty years. On my tow vehicle, if I don't know what the thing weighs I set to manufacturers recommended maximum (which is usually very close to the maximum sidewall pressure on the tire anyway, with my trucks). But to be honest I just about always know what it weighs, within a couple hundred pounds, and there is a free scale down the street from me if I want to double check. Once you do it the first time, you can use a little common sense and estimate pretty closely what you will weigh with different loads.

Door jamb numbers are for ride.
I would go closer to the maximum shown on sidewall. You could drop down a little but not more then 10 pounds.
Then get the rig weighed to get the correct pressure off the tire manufacturer's website for your tires.

acritzer wrote:

VintageRacer wrote:
The manufacturer of the vehicle or trailers maximum recommended pressure. The vehicle is on the door jamb sticker usually, often the trailer is on the data sticker with the VIN. In the absence of that information, the maximum pressure on the sidewall of the tire.

Brian

I understand that. Maybe I didn't ask clearly enough.
-Is it "generally" OK to run slightly under max pressure?
-If you're loaded light you should run "this much under max"

Etc. Simple guidelines that are good rules to follow.
I read a blurb somewhere that suggested not to inflate to max.

It's OK to run less than the maximum pressure shown on the inside of the drivers door jamb if your weight is less than maximum. You can use tire pressure charts if you know your weights. If you do not know your weight pretty closely, be safe and run the the maximum pressure shown on drivers door jamb. Loaded light means different things to different folks. It may mean 90% of maximum to some and 50% of maximum to others. I don't think there is a safe rule of thumb when you don't know your weights other than Maximum shown in drivers door jamb. The other option is to weigh at CAT scale and use tire pressure charts.

You don't need to run the max if you're not towing the max. If you are only putting 600lbs on the rear of a 3/4 ton then 80 psi isn't necessary. If you're maxing out a 1/2 ton then yes air up to the tires max sidewall psi. I would go as far as to say always run max psi in a 1/2 ton when towing because most are near the upper end when hitched and loaded.

What are you towing and what's the load in the truck?

Max sidewall pressure will support the maximum weight the tires are rated for and the tires will run the coolest possible.

Under-inflation makes heat and heat kills tires.

VintageRacer wrote:
The manufacturer of the vehicle or trailers maximum recommended pressure. The vehicle is on the door jamb sticker usually, often the trailer is on the data sticker with the VIN. In the absence of that information, the maximum pressure on the sidewall of the tire.

Brian

I understand that. Maybe I didn't ask clearly enough.
-Is it "generally" OK to run slightly under max pressure?
-If you're loaded light you should run "this much under max"

Etc. Simple guidelines that are good rules to follow.
I read a blurb somewhere that suggested not to inflate to max.

General rule? Inflate each tire to the manufacturers maximum as listed on the tire sidewall. Simple, quick, and efficient. Getting each corner weight and adjusting each tire accordingly is simply not practicle and virtually impossible to do without moving the vehicle. Which negates accurate pressure adjustments, as once you start driving, the tires warm up and the pressure changes!

The manufacturer of the vehicle or trailers maximum recommended pressure. The vehicle is on the door jamb sticker usually, often the trailer is on the data sticker with the VIN. In the absence of that information, the maximum pressure on the sidewall of the tire.

Brian