What's the psi that you fill the tires to?

[dmorlow]

Hi, I have a 95 aurora. My tires say, on the side, 44 lbs psi. I've always filled them to 44 psi. I always thought it was a little high compared to my previous vehicles but didn't think too much about it. Well, my dad needed new tires on his car and asked me to take his car to discount tire and get some new ones. When they gave the car back to me, they said they filled them to 29 psi. His car also said on the tires to fill to 44 psi. Discount Tires response is 29 psi is what the vehicle called for. The tire is meant to be placed on many different types of cars. I asked them about my car (95 Aurora) and they said it's supposed to take 30 psi, not 44 psi. So I've been over filling my tires by 14 psi ever since I've owned it. How is anyone supposed to know that? Or is discount tire wrong?

[rdwrr]

I have a 2001 4.0. I had a hard time finding the correct air pressure also, since I didn't get the car new and there is no sticker in the door jamb. I researched it on the internet and found that most references stated 30 psi was correct. Since other cars that I've owned over the years were about 27/28, I figured that 30 is probably correct. 44 seems pretty high. Maybe that is the max for your tires?

[old goat]

rdwrr is correct. The tire pressure should be set for the weight of the vehicle in order for the tread to wear in a flat pattern across the width of the tread. An over inflated tire will wear in the middle of the tread, an under inflated tire will wear on the outsides of the tread. The tread depth should measure the same across the tire. I use a tread depth gauge for measurments. A vehicle that will see full loads the majority of the time needs more air pressure in order to keep a flat contact pattern with the road surface and vice-versa for a lightly loaded vehicle. The max pressure on the tire is just that. If the pressure needed to have a flat wear pattern excedes the max pressure of the tire, a different tire is needed.
When having tires balanced I leave instructions that the the tires are to be balanced at the air pressure I specify for my vehicles. I know the loads they will see. I make sure the instructions are on the service order with a note that the tires will be re-balanced if the pressure is over 2 lbs off and check the pressure before I pay the bill. Check your gauge against the shops and note the difference. They will vary. I have found that changing the pressure too much after balancing will throw the balance off. This was confirmed by a physics prof friend who ran some simulations from his own curosity. It concerns the shape and weight distribution of a rotating torus (donut shape) from the center of mass. The tires are not consistant in weight distribution and is why they need to be balanced.
dmorlow..you probably have a much smoother ride and will notice better braking in wet conditions.
The ride stiffness and handling of a vehicle is set by the relationship of the spring rate, shock stiffness and spring rate/side wall stiffness of the tire (which is controled by it's construction and inflation pressure). Change tire type or brand and the proper inflation pressure for your vehicle may/will change. The best way is to start at the tire manf recommended pressure for your vehicle and check the wear pattern after a few thousand miles.
In my experiance an under inflated tire will give a mushy ride and steering responce while an over inflated tire will give a jittery ride and skidding during hard stops in wet conditions.
Apologies for the dissertation...I was on a roll. LOL

[The Rebel]

look on the drivers doorjam.

[kayaman420]

WOW !!! 44psi ??? That must have felst like were driving on Flintstones cement tires. lol

30 psi is what the Rora should be. Its on the drivers side door jam as stated above.

When places fill mine to 35 is feels like bricks. 44psi must have been awefully hard and bumpy.

[OldsAuroraMan1]

Really? We have never followed those charts set by GM. Always went to 35 psi with our all of our vehicles ~including our 98 Aurora. My 84 Toronado wore tires Excellent at 35 on the front and 33 rear when the recommended psi was 30 front and 28 rear.

I will surely lower the psi on our Aurora IF it is better!

[OldsAuroraMan1]

Ok. We just put Michelin "Hydro Edge" Tires on our 98 Aurora - LOVE THEM. Quiet, excellent handling and great traction in the snow and rain. PLUS 90,000 mile tread warranty. Here is what Michelin says on their web site about air pressure: "Recommended Pressure
Always inflate your tires to the recommended pressure listed by your vehicle's manufacturer. This information can be found in the owner's manual and often on a placard located in the vehicle's door jamb, inside the fuel hatch, or on the glove compartment door."

So there we have their answer. I suppose if you see your tires wearing on the outsides more than the inside you can raise the pressure to balance out the treadwear - if needed.

[Marc_Aurora_2001]

My 2001 4.0.....36 lbs. all around.


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GM!!! BRING BACK OLDS!!!