[Leader]

I know someone will have the answer to this one...
Is correct tire pressure more critical in low profile tires, such as those on the IS300?
My tires had lost about 2-3 lbs so I topped them off and I noticed (or thought I noticed) a significant difference in ride and handling.
My IS is the first car I've owned with low profile tires and I was just wondering if small pressure changes can really make a handling difference?

 

[Martin]

Since here in NJ we finally had a warm day (75) i checked my tire psi and it was about 30. So i put them to 40 psi(my goodyear's are 44 psi max) and i didn't notice much of a difference. I didn't put in 44 psi because i didn't know if that is the right thing to do.(maybe you are more pron to get a buble with more psi then a little under.) I do know that the correct psi help's in gas milage.

Martin

Black/Ivory IS300

 

[JakeB]

Martin:

If you check in the door jam of the drivers door, you will find the correct tire pressure. 40psi is too high, but I can't remember off hand what the correct pressure is. Just because the max is 44 doesn't mean that you want it that high. Plus, when the tires get hot, the pressure will increase.

 

[Martin]

yes i know the psi will increase that's why i checked and put some in after i was driveing and it was 75 ish out. Wouldn't the Tire itself say what the best psi is? I mean they are makeing them @ goodyear. So why would lexus know better?

Martin

Black/Ivory IS300

Originally posted by JakeB:
Martin:

If you check in the door jam of the drivers door, you will find the correct tire pressure. 40psi is too high, but I can't remember off hand what the correct pressure is. Just because the max is 44 doesn't mean that you want it that high. Plus, when the tires get hot, the pressure will increase.

 

[IS300fan]

Originally posted by Martin:
yes i know the psi will increase that's why i checked and put some in after i was driveing and it was 75 ish out. Wouldn't the Tire itself say what the best psi is? I mean they are makeing them @ goodyear. So why would lexus know better?

Martin

Black/Ivory IS300

The tire pressure on the sidewall of a tire is the maximum allowable pressure as per the tire manufacturer's recommendation. The tire pressure indicated on a car's door jam/owner's manual is what the car manufacturer recommends for that particular car. It takes into account weight, tire wear, handling...etc. Always use the pressure that the car manufacturer recommends.

 

[JakeB]

The tire pressure that is posted on the tire is only the maximum that you should ever have. The car manufacturer has the correct tire pressure, based on vehicle weight, suspension, handling, etc. You should never run the maximum pressure, because you sacrifice handling and risk a blow out. Additionally, you will cause your tires to wear unevenly. Too little pressure will cause the car to ride on the sidewalls slightly, and too much pressure will bulge the middle of the tread and cause wear. You also should never check your tire pressure when the tire is hot...you should always set the tire pressure to the car manufacturers pressure when the tires are cold.

[This message has been edited by JakeB (edited October 16, 2000).]

[This message has been edited by JakeB (edited October 16, 2000).]

 

[AndyL]

Martin,

Out of surprise, Lexus or in general the car manufacturer would know better about the optimum pressure as the tires are the support to sustain the total weight of the car. The maximum tire pressure on the sidewall just tell the maximum load the tire can handle which is a guideline for the car manufacturer to choose the tires of the right load.

My IS has Bridgestone Potenza and I could tell the difference especially in the ride when it is 32psi or 34psi. The recommended tire pressure is 33psi. However, since I am mostly on highway and according to what the tire ship has taught me previously, I just add a little more pressure to the tires to improve the ride and it works.

These low profile tires are indeed more sensitive to the variation of tire pressure.

Andy

 

[HIBBoyScott]

Originally posted by JakeB:
The car manufacturer has the correct tire pressure, based on vehicle weight, suspension, handling, etc. You should never run the maximum pressure, because you sacrifice handling and risk a blow out. ...you should always set the tire pressure to the car manufacturers pressure when the tires are cold.

B]

Unless of course that manufacturer is Ford and you have a vehicle equipped w/ Firestones...