Tire pressure - even level?

noooorb · 04-21-07, 11:17

Hey guys does a car have to be on an even, flat level when checking tire pressure, or is it independent of the weight distribution?

Kriminal · 04-21-07, 11:23

Kinda depends on

a) Do you carry rear passengers ?
b) Do you carry heavy loads ?

If the answer is yes to any off the above, it's required to have greater pressure in the rear tires than the front to cope with the weight.

If not, then I'd just put an even pressure in all 4. Have a look either in the handbook, or somewhere around the gas tank flap - it should tell you your exact requirements.

noooorb · 04-21-07, 11:44

Well the answer to both is no, but it's just that I don't have an even driveway (live on a hill), so I am wondering if I can trust the gauge readings.

mikebai1990 · 04-21-07, 11:50

That's a pretty good question. I've considered that as well. Since I don't know the answer, I would probably just find a flat area and see if it makes a difference

Kriminal · 04-21-07, 12:10

Quote:

Originally Posted by noooorb

Well the answer to both is no, but it's just that I don't have an even driveway (live on a hill), so I am wondering if I can trust the gauge readings.

Hmmm......I would say yes. The readings should still be the same I'd have thought as you wouldn't be losing any air in the tire.

Could you park facing up and take a reading, and then take a reading facing down to see if there are any differences ?

The only problem with driving to a garage to check them, is that you're supposed to check them when the tires are cold.

noooorb · 04-21-07, 12:15

Right + my air compressor is in the garage by the driveway

Kriminal · 04-21-07, 12:22

Quote:

Originally Posted by noooorb

Right + my air compressor is in the garage by the driveway

Ah well, that kinda pi$$es on that idea then

Are your pressures out at all ?

B-Diddy · 04-21-07, 12:30

Maybe this will help. I was checking the air in my tires today and just did a test for you. I set the front tires on my Silverado at 45psi this morning using an Accutire MS-5510B tire gauge.
I went out, jacked one tire up, and checked it again and got 45.2psi The sun is currently shining on the tires when it wasn't this morning so I think thats where the extra .2psi came from.
Either way I basically got the same reading with/without load so it shouldn't matter how its parked.

noooorb · 04-21-07, 12:32

thanks guys for the input & help. very much appreciated

Setec Astronomy · 04-21-07, 05:21

I have also found that it doesn't make any difference whether the weight of the car is on the tire or not...which really doesn't make any sense to me...however, from a fluid mechanics standpoint, that must mean the volume of the tire is the same in both conditions, which means that the tire is bulging out an amount equal to the "flattening" at the point of ground contact. PS...PV=RT

RTexasF · 04-21-07, 05:25

This question inspired me to measure my tires on a flat surface and again on a very slanted driveway. The tires that were "downhill" measured the same as they did on the flat surface. Total distance traveled was roughly 20 feet. They will register the same pressure so don't sweat it.