is 40psi too much at 32 degrees F?

[ron717]

I set my 235/45/17H at 40psi cold at 32 degrees F. I do alot of highway driving, high speed about 100 miles per day. Is this too high? Also day temps when it warms up is around 75 degrees. Door sticker on my A4 recommends only 35 cold.

[VMRWheels]

On a hot day it should rise up around 3-6 degrees above cold temp psi reading depending on driving condition as well.

-Charles@VMRWheels

[Doc@tirerack]

For every 10 degree Fahrenheit change in outside temperature, your tire's inflation pressure will change by about 1 psi (up with higher and down with lower temperatures)

In most parts of the country the typical difference between average summer and winter temperatures is about -50 degree F. That difference results in a loss of about 5 psi, which will sacrifice tire performance and treadwear! So add 1 psi of "cold" tire pressure to compensate for each 10 degree temperature difference.

As long as you do not exceed the "MAX PSI" on the sidewall of the tire, feel free to do what you need.

[Echo3One]

whats the recommended PSI for hot weather. Just moved to Phx, AZ a few months ago. What should I set it for 100 degree plus weather. I have 235/35/19 GE Tires.

thanks in advance

[Doc@tirerack]

Whatever the car's manufacturer recommends.

[ron717]

Whatever the car's manufacturer recommends.

It does not say anything about what temperature to base psi on. So 35psi at 35 degrees F, is going to be 39psi at 75 degrees F. What is baseline temp when adjusting?

[Doc@tirerack]

Normally when the car manufacturer specifies a "cold" temperature to check PSI, we assume around 50 degrees (F), but I've never seen anything in print. Here's some more info that may explain it better than I can;

http://www.tirerack.com/tires/tirete...jsp?techid=147

Indoor-to-outdoor Temperature Variation. Significant differences between the conditions tire pressures are set (the warmth of an attached garage, heated garage or service shop) and in which the vehicle will be driven (winter's subfreezing temperatures) requires inflating tires 1 psi higher than recommended on the placard for every 10° F difference in temperature between interior and exterior temperatures.

Afternoon Ambient Temperature Increase.* Set 2 psi above vehicle manufacturer's cold inflation recommendations when installing new tires or if the vehicle has been parked in the shade for a few hours.

Tire Heat Generated While Being Driven (or at speeds of less than 45 mph).* - Set 4 psi above vehicle manufacturer's cold inflation recommendations.

Heat Generated While Being Driven Extensively (or at sustained speeds greater than 45 mph).* Set 6 psi above vehicle manufacturer's cold inflation recommendations.

Do Not Release Hot Tire Pressure if any of these variables could be the cause of measured tire pressure exceeding the maximum psi branded on the tire's sidewall by the 2, 4 or 6 psi indicated above for the various conditions. This temporary pressure increase is expected and designed into the tire's capabilities.

*NOTE: Tires on a parked vehicle exposed to direct sunlight will appear overinflated due to the heat absorbed from the radiant energy of the sun. Pressures cannot be accurately set on these tires until all have stabilized in the shade.