Is 40 PSI too high for car tires?
No, for most cars a tire pressure of 40 psi is too high. You might find 40 psi suitable for some vehicles, especially if they’re carrying heavier loads or if the manufacturer’s recommendation is close to that figure. However, it’s generally too high for most passenger cars, which usually recommend between 30-35 psi. While you should always stay within this range, you should also never be below 20 psi, or over 50 psi, or you risk serious tire damage (more so than with standard overinflated or underinflated tires to a lesser degree). Your car may have different ideal tire pressures for the front and rear axles.