Checking Your Car's Tire Pressure Haynes Shows You How

Your vehicle's tires are, quite literally, where the rubber meets the road. Modern tires have traction and wear characteristics that were unimaginable 40 years ago, but they do still lose air pressure with time. Also, for every 10 degrees the temperature drops, your tire pressure goes down 1 psi just because the air contracts as it cools.

Properly inflated tires make your car or truck handle better, plus you get better fuel economy and less tire wear; you save money two different ways! Older tires, with tall (75 or even 80 series), softer sidewalls showed a loss of 5 psi pretty obviously, but in a modern stiff low profile rubber it can be hard to spot one that is down even 10 psi.

You should check the air pressure in your tires much more frequently than you do. Haynes typically recommends you check for proper inflation once a week, or every 250 miles, or with every tank of gas. The best time to check the tire pressure is when the tires have been sitting, or when you have driven less than a mile; pressure increases with temperature and the tires get warm from driving. Because highway speeds and long distance is stressful on a tire, check them an extra time before any long road trips.

If you have a regular gas station you stop at to fill up once a week, and are familiar with where their air supply is, take a few extra minutes once a week to check the tire pressure, fill up if needed, and inspect the tires for wear and damage. It is a good idea to stash a tire gauge in your glove compartment and always check with the same gauge; they are inexpensive, but vary greatly from one gauge to another.

This clip is just a sample of checking the air pressure in the tires of a typical car or truck, but your Haynes manual will have more specific instructions if needed.

1. Locate manufacturer suggested tire pressure on door sticker, in owners manual, or in your Haynes manual.
2. Remove tire valve stem cap.
3. Press gauge end to valve stem to read pressure.
4. Add air if needed, or use gauge to release excess air pressure.
5. Replace valve stem cap.
6. Repeat for other 3 wheels.
7. Don't forget to check spare tire occasionally as well.