18 inch PSi question
03-16-2015, 11:00 PM
#2
It's dependent on the tire, but typically 10lbs less than the max rating.
What exactly are you trying to achieve when you're asking for the "optimum" tire pressure?
The more air in the tire, the better the gas mileage
The less air in the tire, the more comfortable the ride quality is.
What is optimum for one person may not be optimum for someone else.
What exactly are you trying to achieve when you're asking for the "optimum" tire pressure?
The more air in the tire, the better the gas mileage
The less air in the tire, the more comfortable the ride quality is.
What is optimum for one person may not be optimum for someone else.
03-17-2015, 06:16 AM
#4
That's the recommended pressure based on the original OEM rim/tire setup. Once you start changing that then it becomes irrelevant and personal preference as Wizard stated takes precedent.
03-17-2015, 08:18 PM
#10
The 255/40/18s on the wife's Lexus also have a 51 psi max.
I think that as you go into the lower profile tires, the psi goes up so you don't bend a rim every time you hit a pothole. You don't have much space for flexing. I hit a pothole with the car last fall and it cost $600 to replace the tire and get the rim repaired.
I think that as you go into the lower profile tires, the psi goes up so you don't bend a rim every time you hit a pothole. You don't have much space for flexing. I hit a pothole with the car last fall and it cost $600 to replace the tire and get the rim repaired.
03-17-2015, 09:28 PM
#14
03-18-2015, 05:18 PM
#19
Whats the OE tire size?
If OE is P205/65R15: OE holds 1,279 lbs at 29 PSI
If OE is P215/60R15: OE holds 1,290 lbs at 29 PSI
Therefore, if you new tire size is 235/40R18 95 Load Index, 34 PSI will carry 1,284 lbs in each tire position, therefore it is equivalent to what your OE tire was meant to carry.
Keep in mind this is cold inflation pressures, and since you have a lower profile tire, it is recommended you keep a good eye on your tire psi since they are easier to damage and lower psi's.
If OE is P205/65R15: OE holds 1,279 lbs at 29 PSI
If OE is P215/60R15: OE holds 1,290 lbs at 29 PSI
Therefore, if you new tire size is 235/40R18 95 Load Index, 34 PSI will carry 1,284 lbs in each tire position, therefore it is equivalent to what your OE tire was meant to carry.
Keep in mind this is cold inflation pressures, and since you have a lower profile tire, it is recommended you keep a good eye on your tire psi since they are easier to damage and lower psi's.
Last edited by risingmist; 03-18-2015 at 05:21 PM.
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