How Does Under Inflation Affect Tire Wear?

By: HowStuffWorks.com Contributors  | 

A tire that is under inflated shows more wear on the inside of the tread than around the edges. If you keep your tires under inflated, you are causing your car (and tires) a number of problems, as well as creating some safety issues.

First, under-inflated tires reduce your fuel efficiency, so you'll be paying for (and burning off) more gas than your car ought to need. Under inflating your tires can also create excessive heat build-up, which not only increases the rate of wear on your tire, but can cause it to blow out entirely. The U.S. Highway Traffic Safety Administration (NHTSA) has given your tire a temperature rating (A, B or C) as part of its uniform tire-quality grading (UTQG) system, to indicate how much heat your tire can handle. However, the UTQG temperature rating assumes you'll keep your tire at its proper pressure. If you're under inflating your tire, you'll have to assume (and guess exactly how much) your tire's ability to manage heat is now much lower.

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The proper inflation level on your tires also affects how much load your car can carry. Every car comes with a tire-load rating that tells you the maximum weight that your tire can bear. However, just as with the UTQG temperature rating, the tire load rating assumes a properly inflated tire (all four of them). An under-inflated tire simply won't be able to carry as much weight.

Your tire's inflation pressure is measured as pounds per square inch, or psi. Your manufacturer's handbook should tell you exactly what the proper psi is for your tires. Buy a simple tire pressure gauge and check your tires' inflation yourself; do this at least once a month. If your tires are below their recommended inflation rate, you can pump air into them at just about any gas station.

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Originally Published: Jun 15, 2011

Underinflate Tires FAQ

What is normal tire temperature?
With normal use — such as driving on the highway — on a 70 degrees Fahrenheit day, your tires will be at around 120 degrees Fahrenheit, according to Caranddriver.com.
What happens if tire pressure is too high?
If you over inflate your tires and make the pound per square in (PSI) too high, you run the risk of causing uneven and extra wear. You're also at risk, if you're carrying a lot of weight or have excessively inflated the tires, of a blowout — and that can cause serious danger.
Is it better to over or under inflate tires?
Both under inflation and over inflation have drawbacks for your vehicle. Under inflating tires can reduce your tread life, reduce your overall fuel economy or even cause tire failure. Over inflating tires can get damaged more easily, wear out faster and potentially even blowout completely.
What will under inflated tires do?
When your tires are under inflated, they're unable to maintain the proper shape. As a result, the tread can wear down more quickly and the tires will bend more while they roll — a detail that increases tire temperature, increases rolling resistance and even lowers your car's fuel economy.
What does under inflating tires mean?
Under inflated tires are those that aren't at the right or recommended PSI; instead, they aren't fully charged. Even having just 6 PSI below the recommended PSI is considered under inflated.

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