Why You Should ALWAYS Keep a Tire Pressure Gauge in Your Car

By now, nearly everyone knows that the single best thing you can do for your car is to keep its tires properly inflated. Not only does it save money and increase tire life, but it enhances fuel economy, handling and performance as well as stopping distance. But by about 20%!

Here’s the formula, courtesy of Tire Rack:

• Filling all four tire pressures to the recommended level by using a good quality pressure gauge will increase fuel economy on average of 3.3% (for every 1 psi drop in pressure over all four tires). This can easily be seen with our “Fuel Saving” calculator which allows you to enter your current mileage and compare it to what you could expect if your tires were up to 3.3% lower in overall pressure. The Fuel Savings Calculator is part of this website so it’s free!
• By keeping your tires inflated at their proper levels, you also get improved handling, increased safety and longer tread life. All told, neglecting proper tire inflation costs American drivers some $2 billion in wasted fuel every year—and that figure could be even higher if you drive a European or Asian vehicle.
• But while most people know they should check their tire pressure on the regular, relatively few do it on a regular basis. So I ask you: How often do you check your car’s tire pressure?
• The answer is probably “not enough” for me to really trust the number I’m about to give you, so feel free to round off to the nearest full percentage point. But according to our own internal sales data here at Tire Rack, only around 55% of all drivers keep their tires properly inflated (we base this number on actual calls we get from consumers asking about how many psi are in their tires).
• So what’s the big deal about tire pressure, anyway? Why should you care enough to keep your tires inflated to their proper levels? Let’s take a look at why tire inflation is important and how it affects fuel economy, handling, tread life and safety.

Getting a Grip on Tire Inflation

To begin with, let’s talk about what causes under-inflation—and its detrimental effect on every aspect of vehicle performance.

What causes low tire pressure?

• There are three main culprits:
• First is under-inflation due to inconsistent air pressures within the tire itself. As tires age they lose air naturally via the permeable rubber that makes up the tire carcass (the underlying structure that holds together the components the tire). Tires can also lose air over time due to small leaks caused by punctures or impact damage. A third reason is an improper tire service, which happens when tires are under-inflated at the point of sale or during installation.
• A second cause of under-inflation is driving on a low pressure temporary spare. Spare tires aren’t designed for extended use and usually contain less tread rubber than your other four tires, reducing their traction capabilities. Driving on a temporary spare. Even if it’s only for a short distance—can damage the temporary spare as well as the other four tires.
• Then there are problems that can occur with high pressures, such as hot spots. An area of excessive heat that can eventually lead to internal tire failure. Or over-deflection (when the tire’s sidewall is deformed beyond its maximum design specifications). Over-deflection can reduce handling and control while also increasing your chances of a flat.

What about over inflated tires?

• Is there such a thing as too much air pressure in your car or truck tires? Yes, but to understand why you need to know more about how and where it causes problems.
• First, though, let’s talk about what happens when we add air to a tire. We increase the tire’s circumference by inflating it with absolute pressure units called psi. This increased circumference makes the cross sectional area rise from A to A’—and that measurement varies based on inflation pressure. It also makes the load-carrying portion of the tire (and contact patch when you’re driving) grow from L to L’.

Conclusion:

Inflating a tire with psi increases its circumference, load-carrying surface area and contact patch.

Now let’s look at the problem with over inflation. Since we know that L increases more than A when we inflate a tire to psi. It makes sense that air pressure levels above the vehicle manufacturer’s specification will decrease. The amount of grip you have because your contact patch is smaller. In addition, any time there’s less contact patch you face a greater risk of skidding or hydroplaning. Since water isn’t completely pushed out of the way like it would be with a larger patch. For that same reason, over inflated tires also face a greater risk of rolling on wet roads.