tire pressure on tow vehicle

gmw photos wrote:

Briand wrote:
Lots of misinformation and confusing information here. If you want to get the most miles out of your tires, most even wear and carry the heaviest load, then inflate tires to the MAXIMUM that they specify on the side wall. I have never had a tire that did not state 2 pressures. Min and max.

I will respectfully disagree with most of that post.

See my earlier post about the P tires on my Nissan truck. And to add to that, the tires ( 80 psi rated, load range E, BF Goodrich LT ) on our F350 diesel dually are maintained at door sticker stated pressure ( 60 rear, 75 front ). The truck is used almost exclusively for towing two different trailers loaded to 13 to 14K pounds. Original tires went 50K miles, and were wearing perfectly even, still had half their original tread. Replaced due to age and beginning to suffer weatherchecking.
Point is, max sidewall pressure is often not needed nor desirable, in my opinion. Y'all's mileage, tires, experiences and opinions will likely vary.

According to manufactures, the only way to acheive the maximum load capacity is to inflate to maximum pressure per side wall. This is true for all tires including P rated. Difference on P rated tires is that they should always be inflated to 36 or 42 PSI depending on XL or not. Then to calculate the reduced load capacity of the tire, you need to do a calculation or look at a table. Neither of these are great ideas. 99.9% of P rated tires are kept at their max pressure.

The way to achieve the best wear and MAXIMUM load capacity of a tire to use the maximum pressure as stated on the side of the tire.

Frankly there is no arguing this point. It is fact.

If you reduce tire pressure, the tire will not be rated to its maximum load capacity and it will wear differently.

In order to determine exactly how much you should inflate your tire based on a certain weight load is a calculation that not many people can do. It is much easier to inflate them up to max as stated on the tire sidewall or other official tire manufacturer's documentation.

Briand wrote:
Lots of misinformation and confusing information here. If you want to get the most miles out of your tires, most even wear and carry the heaviest load, then inflate tires to the MAXIMUM that they specify on the side wall. I have never had a tire that did not state 2 pressures. Min and max.

I will respectfully disagree with most of that post.

See my earlier post about the P tires on my Nissan truck. And to add to that, the tires ( 80 psi rated, load range E, BF Goodrich LT ) on our F350 diesel dually are maintained at door sticker stated pressure ( 60 rear, 75 front ). The truck is used almost exclusively for towing two different trailers loaded to 13 to 14K pounds. Original tires went 50K miles, and were wearing perfectly even, still had half their original tread. Replaced due to age and beginning to suffer weatherchecking.
Point is, max sidewall pressure is often not needed nor desirable, in my opinion. Y'all's mileage, tires, experiences and opinions will likely vary.

With P tires, which I suspect your's are, I would air the tow vehicle's tires up to the max on the sidewall.
My new truck, on the other hand, came with LT tires with E load range. On it I just keep the tires at the recommended inflation amount on the A-pillar yellow sticker, 50# front and 60# rear. I have a lot of excess capacity with my tires.

P tires don't have so much excess capacity, plus max air in P tires will help stiffen the sidewall as much as possible.

Bobbyg2013 wrote:
should I increase the rear tire pressure by 10 psi, on my truck's tires or leave at the suggested 35 psi that is shown on the sticker on the door jam?

“The National Highway Traffic Safety Administration has a legislative mandate under Title 49 of the United States Code, Chapter 301, Motor Vehicle Safety, to issue Federal Motor Vehicle Safety Standards (FMVSS) and Regulations to which manufacturers of motor vehicle and equipment items must conform and certify compliance.”

The FMVSS regulations are often misquoted or quoted out of context, leading readers of internet forum discussions about tires to come to conclusions about their tires that are unsafe, unapproved and unjustified.


“What Air Pressure Should Be Used?”
“The pressure your tires require is determined by the vehicle manufacturer in conjunction with the tire manufacturer and is based on the vehicle’s gross axle load. Every vehicle is required by federal regulations to include a tire information placard. This placard may also be referred to as the tire certification label or federal tire tag. Vehicle manufacturers are required by federal motor vehicle safety standards (FMVSS) to apply tires of a suitable size, load range and inflation pressure (as shown on the tire information placard) that are capable of supporting no less than the gross axle weight rating (GAWR). Consequently, the vehicle manufacturer’s specified tire inflation pressure is not arbitrary; it is established by federal safety regulations (ref: Code of Federal Regulations 49, 571.120, and Part 567).”

The quote above is from a major tire manufacturer. Because the vehicle manufacturer’s tire inflation pressure is established as a minimum standard for the tires fitted to your vehicle, the load capacity they provide is also a minimum standard.

Lots of misinformation and confusing information here. If you want to get the most miles out of your tires, most even wear and carry the heaviest load, then inflate tires to the MAXIMUM that they specify on the side wall. I have never had a tire that did not state 2 pressures. Min and max.

That spare is probably the "donut" type. Temporary for use to get to a place to fix the real tire.

coolbreeze01 wrote:

APT wrote:
This sticker lists what the vehicle manufacturer recommends for tire pressures as a compromise of ride/handling and comfort. It also must be capable of handling the vehicle's load at GVWR.



Many people have experienced that a little higher pressure when the vehicle is closer to GVWR than unloaded provides a better ride and handling.

Worth noting that the spare is filled to 80psi. Curious what the OP's spare tire is aired too?

Pressure questions have been answered well here.
Just another story.
I traded for a new F150 and specified LT tires. Had been towing with P tires and was tired of getting sway just from the squishy tires!
Got the new truck home, and looked .... They had tires on it with a model name LT something or other. The tires were P rated.
Called them back and had to actually educate the salesman about the difference!
Got the correct tires (actually LT rated)on it a couple of days later.
I still can't believe they didn't know the difference, but were maybe hoping I didn't!

hawkeye-08 wrote:
To carry the load the tire is rated for, you need the max psi on the sidewall. If you are carrying less than that, adjust accordingly. P-metric tires are often filled to recommended pressure on door jamb sticker, but that is not for the max load, that is for comfort.

Partly true...The pressure listed on the door jamb sticker is not for "comfort", that is the pressure required to support the load of the vehicle and its contents loaded to the full GVWR.

If the tire says 44 psi max on the sidewall, the tire will carry the max load listed on the tire's sidewall at that pressure. If the door jamb sticker says 35 psi, then that's all that is required to carry the max rated load of the vehicle. Now whether you are over your max rated load with the trailer is another question....

Many report better stability via the stiffer tires running at the tire's max rather than the the mfrs inflation on the door jamb.

FWIW, this was exactly the issue with Ford and Firestone on the Explorers years ago...Ford rated the Explorer with a low GVWR and spec'd tire pressure to match. The roominess of the SUV had folks unknowingly overloading their Explorers and causing blowouts which were blamed on the tires since nobody actually weighed their SUVs packed full of stuff. Firestone's response was that the tires should have been inflated to the max sidewall pressure, not the lower number on the door jamb.

So (these numbers are just to illustrate) if the tire's sidewall says it can carry a max load of 2000 lbs at max pressure of 44 psi, but the vehicle manufacturer specs a rear axle rating (RAWR) of 3000 lbs, each tire only needs to carry 1500 lbs when the axle is at max capacity. So the vehicle mfr can spec a pressure of say 35 psi on the door jamb, since the tire will safely carry 1500 lbs at 35 psi.

Increasing the tire pressure from the vehicle's specified 35 psi to the max on teh sidewall will increase the carrying capacity of the tires but NOT the vehicle.

It is my 2011 Chevrolet Suburban 2500. The overall tire sizes are the same, 265/75R16 and 265/70R17.

Bobbyg2013 wrote:
should I increase the rear tire pressure by 10 psi, on my truck's tires or leave at the suggested 35 psi that is shown on the sticker on the door jam?

What does your owner's manual say?

35 psi is normally for a standard load Passenger tire. Is there something on the sidewall that says you can go higher than 35 psi?

FastEagle