Tire pressure

[NorthGeorgia]

My vehicle states on the tag/sticker that my tires air pressure should be 35lbs. I've always kept it at that. A while back the Ford dealer did my one and only 'free' oil change and whatever else they do. Admittedly I had not checked my air pressure due to the tires having 'nitrogen' so supposedly the air pressure does not fluctuate that much? Today I checked and the pressure was 38lbs. Well, the Ford dealer had to have done that.

So my question to you experienced Ford owners(I'm a newby) does Expedition need to be more than the 35lbs even tho that's what's stated on the tag/sticker?


thanks

 

[1955moose]

Tire air pressure is dependent on a few things. Number 1 that's paramount is how much weight are you carrying? Vehicle weight, how many passengers? And their weight. Any gear you have in your Suv. If you pull a trailer, or boat then the number changes again. Say for example the pressure on sidewall says 50 pounds maximum, a good rule of thumb would be 10 to 20 percent below that number cold tire. My Kumhos have that 50 psi max, I run mine at 42 to 44 cold. The worst thing you would want to do is run a tire too low on pressure. Heat builds up on a low pressure tire, and can and will cause a blowout. The advantage I find with keeping pressure a little above factory sticker, is it gives you that bumper, in case you lose air. Tires should be checked at a minimum every 2 weeks. These days with stiffer sidewalls, a tire that's 10-15 pounds low can look fine to the eye, but be a disaster waiting to happen. Leave them at 38 psi, your fine.

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[chuck s]

The Expedition will carry the maximum rated load at the tire pressure on the sticker: 35psi. Increasing tire pressure does not allow the truck to carry more than that. To carry more than the ratings requires suspension changes, not tire changes.

Passenger car tires are inflated to less than the tire's maximum sidewall pressure to provide a more compliant ride. Guys who put LT tires on their SUVs are kidding themselves, the axle ratings don't change and neither goes the GVWR.

Nothing complicated here, it's on the sticker. 35psi.

 

[cullinan18]

If you're not running OEM tires the sticker is useless Also, remember the Firestone /Ford Explorer history? I inflate based on my tires and my comfort level, not the sticker.

 

[99WhiteC5Coupe]

The Expedition will carry the maximum rated load at the tire pressure on the sticker: 35psi. Increasing tire pressure does not allow the truck to carry more than that. To carry more than the ratings requires suspension changes, not tire changes.

Passenger car tires are inflated to less than the tire's maximum sidewall pressure to provide a more compliant ride. Guys who put LT tires on their SUVs are kidding themselves, the axle ratings don't change and neither goes the GVWR.

Nothing complicated here, it's on the sticker. 35psi.

View attachment 25989

I have seen people inflate tires to the maximum pressure on the tire’s sidewall - but this does not account for the pressure increase as the tire heats-up, which then exceeds the recommended pressure.

Vehicle manufacturers spend considerable time and engineering effort to determine the type of tire and inflation pressure. I agree with setting the cold tire pressure to the recommended pressure on the vehicle’s tire label.

 

[1955moose]

Chuck the sticker is for the basic vehicle weight with all seats filled. Things can vary. Summer is different than winter, high performance tires are different pressure. The oem pressures are also set up for optimum ride quality. Nothing is black/white when it comes to air pressure. Light truck tires or Lt, are definitely higher capacity than passenger tires. You need to get your facts straight before giving advice. I worked in the tire business for over 30 years, we would never put a passenger tire on a vehicle that had a Lt rating, that would open us up to lawsuits and worse. You can always go higher on a load or speed rating, but never lower. I pride myself as me and my crews never had a legal incident. We never dropped a speed rating, or a ply rating on truck tires, just to make a sale. Sleeping well with a conscience is more important. I've seen what happens with a wrong tire, or pressures can do. You educate your customers , what they do after that, well! It's like teaching your kids.

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[chuck s]

Clearly LT tires have a higher capacity than P-tires in the same physical size. This is indisputable and also immaterial as it doesn't change the capacity of the truck. It's a "so what?" item.

The P-tires on my Expedition have a maximum carrying capacity of 2756 pounds at 51 psi. Each. That's 11,024 pounds total. The same size LT tire has 3415 pounds capacity an 80 psi. 13,660 total, nearly twice the GVWR of the truck. Note these are cold tire pressures, the tire pressure will harmlessly increase to a higher pressure as the tire warms up on the road -- all tires are designed to do this safely. This is why air should never be released to bring a hot tire down to the specified pressure as it will be underinflated when cold and that can cause massive over-pressure as heat in the tire builds up as the layers move inside.

The GVWR for the truck, though, is 7,500 pounds which is obtained with the OE tires at 35 psi. GVWR is the maximum allowable weight of the vehicle loaded. Clearly the P-rated tires can handle the maximum weight of the truck. In fact they can handle it at a more comfortable, non-truck like ride (as provided by LT tires).

Increasing the GVWR takes more than tires. Running over than the allowable weight requires more tire capacity and there's an "extra" 3524 pounds of tire capacity already in those P-radials with boosted tire pressure. Truck is still overloaded though.

-- Chuck

 

[coolzzy]

I air up my rear tires to 50psi when towing my travel trailer since the oem tires have such a soft side wall and I'm running at max tongue weight so any additional stiffness helps. Even with a properly setup wdh, max air pressure on the oe tires makes a difference. It also gives me slightly better mpg when highway traveling.

 

[chuck s]

This will usually take some radial tire squirm out of the rear. I commonly bump the cold pressure to 40psi when towing for just this reason. Doesn't increase the GAWR, though.

-- Chuck

 

[Plati]

IMHO

re: Original OP question ... follow the (35) recommended psi, measured cold as advised if running P (Passenger rated) tires. Hopefully of the same tire size as on that tag.

Tire pressure is changed by temperature, so if the dealer set the pressure when it was cold out and you measure it when its 50 degrees hotter, the pressure will be approximately 5 psi higher.
https://www.tirebuyer.com/education/tire-inflation-pressure-and-temperature# I like to set my tire pressure at a median temperature like 50 so its sort of OK at 80 or 20 but check it in hot weather (95) and cold weather (zero or minus)

Its also possible the dealer made mistake either in the setting or the equipment used to set it.

When running LT (light truck) tires, you NEED to run higher pressure even if vehicle LOAD doesn't change and its a bit complicated to arrive at the proper number.

As usual, if I'm wrong please correct me.

This all makes me wonder what the effect of elevation changes are on tire pressure. If I set my pressure at home (500 foot elevation) and drive up to the Alpine Loop ... will the tires need some air released or will the tire pressure change or is anything adviseable. Reason I wonder this is I have an air mattress that almost explodes when I fill it with the right amount of air at home and then drive up to 13,000 foot elevation. I really have to let air out of it as I climb and add air as I descend.