When it is not enough pressure the outside of the tread wears more, and too much pressure the inside middle of the tread wears more. 5 PSI difference is nothing really to be concerned about. 20 PSI low or high on a 40 PSI tire is something to worry about.
In any case running a tire over it's maximum rated pressure is a bad idea, you are running the front over their rating. When you do that they are more easily damage by road hazards and heat. Run the tires at the pressure the owners manual recommends unless you have tires that are not stock, but never over their rating. Larry
In any case running a tire over it's maximum rated pressure is a bad idea, you are running the front over their rating. When you do that they are more easily damage by road hazards and heat. Run the tires at the pressure the owners manual recommends unless you have tires that are not stock, but never over their rating. Larry
Just want to add in another opinion. My grandfather has ran 15-20 psi over on all of his tires for 40 years trying to get better gas mileage.
There is a difference in the tire pressure that is recommended for the car and the maximum pressure printed on the side of the tire. The people who make the tire probably know how much pressure it can safely hold. Larry
The owners manual or label on the door gives the tire pressure the Pontiac found to be best all around for wear and handling. The pressure on the tire gives the max pressure that the tire can safely hold. If you go over the pressure on the side wall you are over the safe pressure for that tire. As covered above that will cause wear and handling problems, and when driving the car the tires will heat up and cause the pressure to go higher. This could cause the tire to blow, or the bead to pop if it is to high.
Some people use the chalk method to find the ideal pressure for their tires, but you shouldn't go over the max pressure on the side wall. The best that will happen is excessive tire wear, the worst is massive tire failure while driving.
30 PSI front and rear. Mid engine cars feel 'nervous' in a straight line due to weight distibution. Check for worn suspension components and proper alignment.
My tire pressure is set to the outside temp, or the driving conditions. If it is 90 degrees out, I run a lower pressure. About 5 psi. When the seasons change, I run a few more pounds.
If I am planning on a spirited drive in the dry, I increase pressure before the run.
Your car may be handling weird because of your mismatched tires. If the maximum tires pressures are that different, then they most likely have very different handling characteristics. If your tires are so dissimilar that they cause handling problems, then you need different tires.
Anyway, the best air pressure to run in your tires is whatever results in even wear across the tread.
[This message has been edited by Blacktree (edited 09-08-2013).]
Originally posted by RilesOfSmiles: My front tires are rated at 35 psi max press and my rears are 44 psi max press. I keep all 4 at 40 psi. Is this a good idea or not?
No.
Could something go wrong? Maybe. Front is 40 psi cold then add more pressure when heated. Will void any warranty by over pressure.
The car seems to wander a bit if the pressure is much lower Bad tire(s), Iffy suspension, bad cradle bushing, etc can cause this. Mix brand/model of tires on a car won't help.
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Originally posted by BlackEmrald: This is incorrect. That is the MAX pressure it is safe to run at. Once again, the number on the tire is MAX, not recommended. For recommended pressure, refer to the sticker in the driver door jamb.
MAX Cold pressure it is safe to run at. Many tires leave out cold on sidewall label. Cold means tire and rim are cold... about weather temp at the time.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
MAX Cold pressure it is safe to run at. Many tires leave out cold on sidewall label. Cold means tire and rim are cold... about weather temp at the time.
