Correct Tire Pressure Explained

Maintaining proper tire inflation is one of the most important things you can do to save on costs and ensure your car performs at its best. Having the right tire air pressure helps your tires last longer, perform better, and promotes better fuel efficiency.

Checking your tire pressure regularly is important because all tires will lose pressure over time, roughly around one to two pounds of air pressure a month. If you live in New England (or anywhere else that sees the best of all four seasons), it’s even more important to regularly check car tire pressure as, due to the variable weather conditions, your tires’ air pressure will change by around one pound per square inch (psi) every 10 degrees.

So what’s a normal tire pressure and how can you ensure your vehicle is operating safely? Read on for everything you need to know.

Understanding Correct Tire Pressure

When we talk about tire pressure we’re referring to the amount of air inside the tire, which creates internal pressure that supports the weight of the vehicle. Pounds per square inch (psi) is the specific unit of measurement used to quantify tire pressure.

So how do you find the right psi for your tires? Well, it’s important to understand that the psi number on your tire isn’t the recommended pressure, but is the maximum psi amount for that tire. Keeping your tires at maximum pressure isn’t recommended due to the risk of overinflating.

To find the actual recommended psi for your tires, you can check your vehicle’s owner’s manual or the tire information placard located inside the driver’s door jamb. If your vehicle’s tire placard isn’t in the door jamb, it may be located in:

• The glove box
• The fuel filler door
• The center console door

Either the placard or manual should list the appropriate, normal tire pressure for both the front and rear tires, as they may be different. Every vehicle will have specific requirements. While most passenger cars’ recommended pressure levels will fall between 30 to 35 psi, certain vehicles will fall outside of that range.

Here’s an overview of recommended tire pressure for 10 of the more popular vehicle makes and models.

These values are typical for standard conditions and loads. Check your own vehicle’s owner’s manual or tire placard for precise information about what your tire pressure should be.

Importance of Correct Tire Pressure

Maintaining the recommended tire pressure ensures that all of your tires wear evenly (as much as possible) and enhances vehicle safety and stability. When tire pressure is too low or too high, your tires will have a reduced tread area to grip the road. Underinflated tires will “pinch” in the middle, leaving only the sides of the tire in contact with the road. Overinflated tires lift up the sides, leaving only the very center of the tire in contact.

Proper inflation allows each tire to have the largest possible area of contact with the road, which:

• Improves fuel efficiency, resulting in reduced costs and environmental impact
• Prolongs tire lifespan and prevents premature wear, keeping more tires out of landfills
• Provides maximum safety in wet conditions by channeling water as intended
• Reduces the risk of tire tears or blowouts

Consequences of Underinflation vs. Overinflation

Why worry about a little underinflation? Driving on underinflated tires not only causes uneven tire wear, it has a direct effect on the quality of your driving. Underinflated tires can cause:

• Decreased fuel efficiency — The increased rolling resistance and friction with the road will force your vehicle’s engine to work harder, which uses up more fuel.
• Reduced handling — With reduced, uneven contact with the road, your vehicle will experience decreased handling and steering and increased braking distance.
• Higher risk of tire failure — Uneven wear on your tire’s tread reduces its life and can lead to overheating, tread separation, and even blowouts.

Why not just over inflate your tires to be safe? Because there are consequences for overinflation as well. Besides uneven tread wear on the center of your tires, overinflated tires can result in:

• Harsher rides — Tires act as a buffer between the road and your car’s suspension system. When they’re overinflated, they can’t absorb shocks effectively, transferring more pressure to the suspension.
• Reduced traction — With less rubber on the road and less give on the sidewall, your road grip is reduced, which directly affects acceleration, handling, and braking.
• Higher risk of failure — Increased wear on the center of the tire creates bald spots, which won’t dissipate heat as effectively, putting you at risk for a blowout.

How & When To Check Tire Pressure

Your tire’s pressure changes all the time, due to:

• Differences in air pressure in warmer and colder temperatures
• Natural air pressure loss that occurs over time from permeation through the tire sidewall
• Changes in air pressure when driving through different altitudes
• Small leaks caused by damage from road hazards (nails, screws, and the like)
• Excessive load weight

Aside from natural air pressure loss over time, the biggest impact on your tire pressure when driving in New England is the four seasons and sudden changes in temperature. With seasonal temperature changes that can bring as much as a 50 degree shift, it’s highly recommended to check your tire pressure once a month.

Here are a few other tips:

• Always check your tire pressure before driving instead of after a trip. Tire temperature increases during a drive, which will also affect its air pressure, providing an inaccurate reading. If you do need to check your tire pressure after driving, try to wait three hours to allow the tire to cool down.
• To adopt a regular schedule for checking your tire pressure, associate it with other vehicle care, such as every other time you gas up.
• Even if it’s not part of your regular tire pressure check, you should check tire pressure before long trips or after drastic weather changes.
• If you have to test or add pressure while on the road, take care when using public air gauges or compressors, which may be worn or damaged from repeated use.

Here’s a step-by-step guide on how to check your tire pressure using a pressure gauge and to adjust it using an air compressor or air pump.

1. Unscrew the valve cap on the valve stem. Place the cap somewhere secure where you won’t misplace or lose it.
2. Firmly press the tire pressure gauge into place onto the valve stem. You’ll hear a quick release of air pressure as the gauge connects.
3. Check the gauge’s readout against your vehicle’s recommended tire psi. If you need to add or remove air, be sure to check the pressure level again to ensure it’s where it needs to be.
4. To add air, attach the nozzle to the valve stem and seal it using the locking mechanism on the head of the nozzle.
5. Make sure the nozzle and the valve stem are sealed properly and turn on the compressor. If you hear air escaping, turn off the compressor, re-seal the nozzle, and try again.
6. Use the compressor or air pump and inflate to the proper psi using the compressor/pump’s included psi gauge. If your compressor or pump doesn’t have a psi gauge, fill for 5–10 seconds and then check with a manual tire pressure gauge.
7. When you reach the right level of psi, turn off the compressor/pump and remove the nozzle head from the valve stem.
8. If you happen to over-inflate your tire, you can release some air in small increments by depressing the center valve pin (the brass needle in the middle) using a tool, your tire gauge, or even a fingernail.
9. Don’t forget to replace the valve cap to protect the valve stem from corrosion and debris.
10. Repeat the process for the remaining three tires. It also doesn’t hurt to check your spare tire, especially before road trips.

Tips for Properly Inflating Your Tires

Here’s a few additional tips to ensure your tires are performing at their best:

• All cars manufactured after 2007 come with an automatic Tire Pressure Monitoring System (TPMS). However, don’t use the warning light as a signal for your regular tire pressure checks. TPMS alerts usually trigger when a tire’s pressure is about 25% below the manufacturer-recommended levels, and it takes as little as 5% underinflation to experience the harmful effects of driving on underinflated tires.
• Always follow the manufacturer’s recommended pressure levels, listed either in the owner’s manual or the tire information placard. Do not fill a tire to the psi level listed on the tire’s sidewall.
• Fill your tires slowly and evenly to avoid overinflation. Slow down when you get close to the psi level you want.
• Your valve caps prevent air leakage while driving and also keep your valve stems safe and clean from debris. Replace them ASAP if you lose one.

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