hi, so the recomended tire pressure for my tires are 80psi, this seams a bit much.
what are you guys running yours at? whats a safe max?


and on a side note, to check the fuel pressure, do you check it at the tire valve type thing on the fuel filter?

thanks.

 

You're truck (what ever) will usually have a decal on the drivers door, or on the door jam giving a recemended tire size, and air pressure.
If you're driving a, F350 (I say this cause you say 80 lbs/10ply) you may see that the decal will say something close to 65 psi in all four/six....... This is plent for a 10 ply (Load Range E) tire. It will give you a way better ride then 80 psi.
If you're going to load the truck down heavier, add more air. If you're driving a dually, check into getting some "Cat's Eye's" you can check, and change both tires on a side at a glance.
Too many tire shops, see that the tire will safely take 80 psi, like a 10 ply, and just set the air pressure at that. You have more load range to use, but the ride is gone.
Bob

 

80 PSI give the best MPG
80 PSI gives the best load carrying capacity

This is assuming you are running 235/85-16 E rated tires.

You should run the pressure listed on the sidewall of any tire.

To check fuel pressure, remove the valve core and attach a pressure gauge there.

 

Way back when I worked for a tire store, we would set tire pressure on passenger car and 1/2 ton and smaller tires to 32-35 psi. We would set 3/4 ton and 1 tons to 45-50 psi and would note that to the owner. These pressures gave the best ride characteristics and tire wear. The only time I would go to max psi is if you plan on hauling or towing. The pressure listed on the sidewall is max recommended at the max weight. Someone like Dave who is hauling at full capacity should be running them up that high. But if you're main use is as a commuter, the max pressure is unnecessary. Pump them up if you plan on carrying a load.

The pressure listed on the door sticker is a good general rule of thumb. But, it is just the automotive industries version of CYA. My truck weighs 8200 lbs. They don't take into account that I may load another 6-8K in the bed. I run my tires at 45 psi normally and bump them up if I am carrying a big load or towing.
An old school trick is to set your pressures and then drive through a puddle and check the contact patch and adjust accordingly.

Jason

 

I run my 10 plys @60PSI front/70 PSI rear.

It rides a little better, and if I need to put a lot of weight on them. I bump them up to 80 PSI.
80 PSI is just to dang hard for daily driving. The front end slams hard on every little bump.

 

That one's a myth. How do the tire manufacturers know exactly what vehicle a tire is being mounted on? A particular tire size can fit a wide variety of vehicles and that's why you want to use the vehicle makers recommendations as a starting point and go up from there depending on your use. No way I'll be running 80psi in all 6 tires on my dually! My dental insurance isn't that good!

Just an FYI.

 

thanks guys, yeah sorry, thought i had my truck info in my sig.

thanks

 

My teeth are gone, have been for years.
So 80 PSI is no problem for me.

Although it is a much harder ride, max inflation does decrease the rolling resistance.
Decreasing rolling resistance does increase the MPG.
Also max inflation increases the diameter of the tire, so distance traveled per revolution is farther, once again increasing MPG.

The last statement may not be true for overdrive equipped vehicles, but those of us with direct drive will take every possible MPH we can get out of the same RPM.

I haul enough weight often enough that mine are always at max inflation.

PS. My door sticker says 80 PSI cold inflation pressure.

 

Dave, you need to put an overdrive in there, otherwise I might start saying that my truck can out run yours.

The sticker on mine says 50 PSI for the front and 80 on the rear, maybe its a 2wd thing....

For comparison, our 1997 rav4 has tires rated at 44psi, the door sticker calls for 25 (all four).

 

Dave is right about about the MPG factor. Tests have also shown that vehicles with tires inflated to max psi have shorter braking distances than those running less pressure. The lower the tire pressure,the greater the stopping distance.Think about this also, if you have a 1990 model vehicle for example,do you think tire technology is the same now as it was 18 years ago? I don't think so. Look at the lawsuits against Ford over the Explorer roll over issues. Look at the lawsuit Ford had against Firestone over this. Look who won and why.

 

You are right mileage will increase because of the reduced rolling resistance. But on that same token, your braking and cornering performance will not be better. In fact, it may be worse. If you are running max psi, your tires are only contacting the center of the tread. Smaller contact patch= less grip. Likewise, if you are running too low of pressure, the same problem will result, beyond a certain point.
This is especially true in light truck tires as there is a huge variance in vehicle weights and load capacity versus actually use.

Jason

 

I would agree with your logic in the case of either over or under inflation. However, if you do not exceed max recommended pressure I don't think it will have that much impact either way.

 

hi everyone, i've noticed if the tires are under inflated for the weight of the vehicle the tires will wear more towards the sides of the tread and not as much in the middle.if over inflated the tread will wear down the middle and not as much on the sides. norm

 

Exactly, well put!!
My 35's are a load range D and are rated at 3195 lbs @ 50 psi. So it has roughly 6400 lbs per axle capacity and a little under 13K total. My truck weighs about 8200 lbs full of fuel and myself. I can't remember the axle weights, but we'll say its 5K lb F and 3K lb R. So, if I run max psi on all tires, I will lose a percentage of the contact patch because the excess pressure is causing the tire to run on the crown of the tread. With some calculation, I figure I can drop safely down to 35-40 psi. I run 45 psi front and rear, because I regularly haul heavy loads and I don't want the headache of adjusting tire pressures. Plus, tall sidewall tires tend to wallow at low pressures. My tires wear evenly at this pressure (65K miles from my last set) and the handling and stopping characteristics are fine.

My door lists 58 psi on the front and 80 psi on the rear with E rated 235/85R16's. Manufacturers list these pressures to protect themselves in case you overload an underinflated tire and have an accident. Most trucks are bought with the intent to haul. So they list the maximum pressure to cover the GVW of the truck, hence CYA. Passenger cars are rated differently as they don't list GAWR's. They list XX psi for vehicle weight and passengers and cargo not to exceed XXXX lbs. This is why you see many passenger cars with psi ratings in the low 20's, even if the rating on the tire is for 35 psi or more. They figure that most smart people are not going to attempt to haul a cord of firewood in their Taurus.

Jason

 

But then again.......