The best time is when the tires are cold — after the car hasn’t been driven for at least one hour — and when your car is in a garage or shaded area.

That will give you a better reading than if you check the pressure shortly after driving. Air expands as it gets warmer, so the pressure will be higher right after you stop. If you drove for an extended period at highway speeds, it will be several pounds higher.

Tire_cold

Bear in mind that the ambient temperature also affects tire pressure. The Rubber Manufacturers Association says air pressure inside tires drops one to two pounds for every 10-degree decline in the outside temperature and rises a corresponding amount when outside temperatures increase. If your car is baking in the midday sun, the tires bathed in sunshine will have higher readings than the ones in shade, so try to check pressure when that isn’t a factor.

Don’t be obsessed with keeping the tire pressure spot on with the manufacturer’s recommended level. Pump an extra pound or two of air into your tires, and you’ll have a little cushion for when air starts escaping, as it eventually does in all tires. A little more air is better than too little. Just don’t overdo it.

Learn more

Answered by Rick Popely on April 18, 2010 in How Does That Work? | Permalink

Search Results

Ask.cars.com Search Results for

Search

See if your question has already been asked and answered

Thank You!

Your question has been successfully submitted to Ask.cars.com. It will now be reviewed by our editors and we'll answer it soon if we think it's a useful question. You will be notified via e-mail when the answer is posted. Ask.cars.com tackles your questions about new cars and the car-buying process. Unfortunately we can't answer questions regarding:

  • Used cars.
  • Most aftermarket products.
  • Mechanical issues. You can visit our friends at Car Talk to discuss your mechanical problems.
Thanks for your interest.

Ask

Have our experts answer any of your questions about new cars.

Email us at [email protected]

Maintenance Advice
Get answers from the
Car Talk Community