Tire pressure?

[Melelio]

Silly question, I'm sure, but...

If my car is rated for 30psi in the tires, but I put on tires that have max. 44psi, do I still use just 30psi?

What is the effect on the tire if you have it 14psi lower than it's max?

Any answer that seems too obvious to you probably is not to me, so any answers needed!

Thanks

[jayhawk]

No affect at all...in fact for best fuel economy, tire wear and and performance you should keep them between 30-35 psi. Too low and you will have great traction but fast tire wear and poor fuel economy, too high and you will have poor traction, fast tire wear, and good fuel economy. 44 psi is the absolute maximum the tire can hold before it bursts off the rim. Keep in mind that you gain 3-5 psi when the tires get warmed up from normal driving. I myself keep them at 35 psi normally, and 25 psi when I go crusing on my towns local strip.

[Melelio]

Hi Jay,

Thanks for the reply. So you say, even though my car specs say 30psi, I can up my tire pressure? That doesn't affect car handling, etc.? What is the car spec for, for tires, anyhow? So that we don't put Range D\80psi tires on 'em? (Like my big mean Cummins Diesel has?)

[Colin]

Jay pretty much summed it up . To be sure check the sticker on your drivers door for the pressure for your car tires , ( my 2000 says 32 psi ) . Check them when they are cold , before driving too far . They will expand when hot . It's better to be a pound or two over than under inflated . ;)

[Rayz]

FYI:
Handling Adjustment Reference Chart
For More Understeer* For More Oversteer**
Chassis Feature Adjust As Indicated Adjust As Indicated
Front Tire Pressure Lower Higher
Rear Tire Pressure Higher Lower

* Understeer—The car pushes or plows when you turn, and front wheels lose traction first.

** Oversteer—The rear of the car is loose (loses traction first).

[BBT]

The load the car is carrying also has a bearing on the amount of air. 44 psi is the max at full load - for the tire - not neccessarily for the car. If you load your car up to go on vacation, be sure to add some air to the tires. How much depends on how much weight is on the car and the tires. You'll have to judge it by feel mostly, and by the look of the tire. But I don't think I'd ever pump a tire up to its max rating just for everyday driving.

The ratings the car manufacturer give are just a good compromise setting for the car weight, full load weight, suspension & braking designs and the tire they select. After that, it becomes very much up to you and how you drive, what kind of ride you like, the size & type/design of tire you install and so on. Again, a lot of it is judgement.

[Chain]

Actually I run 40 in the fronts and 37 in the rear. The front always looks low because of the motor. Not sure if this is the correct methode. But it seems to make the tire wear even this way.

[BBT]

Whatever rocks yer car. I'd expect that to be awfully harsh riding, but it's your choice.

I run about 30, maybe 31 in the 225/50-16s on my 95 GT. Gives me the compromise I'm happy with - even wear, good ride, good grip if not ultimate transitioning, but I can live with it as I don't drive on a lot of swoopy, twisty roads.

[Colin]

Originally posted by BBT
Whatever rocks yer car. I'd expect that to be awfully harsh riding, but it's your choice.
Also makes the tire more likely to be damaged by impacts and punctures from road debris . They would also be very close to the Max pressure once they get warm and expand . But some people like the handling of a stiff tire , so to each his own . :D

[Chain]

What I have noticed is if I run the fronts down to 34 or 35 psi I start wearing the outside of the tire down. I get uneven wear. I would like to run them lower. Much smoother ride.

[goldfinger]

I run my fronts @ 40PSI and the backs @30PSI (44 is MAX).

I actually checked the backs the other day and they were down to 22PSI! There's literally no weight over them so they were still wearing just fine and looked full. If I run the fronts any less than 40, they squat and would wear on the outside. The ride is about what I would expect for a low profile tire.

It never ceases to amaze me how many people look for the number on the side of the tire and start filling. They fail to account for the fact that when the tire gets warmed up it will be well over the maximum recommended PSI. :roll2: Mostly because they don't know that number is the maximum!