A tire’s tread life is just that: how long its tread will last. Manufacturer warranties (learn more about how tire warranties work) cover tires for tens of thousands of miles. But the actual longevity of any given tire is impossible to predict and is dependent on a variety of factors—from how aggressively you drive, to the tire’s rubber compound and tread pattern, to how well you maintain your vehicle and tires.
Tire manufacturers try their best to predict the treadlife of their tires based on each tire’s rating in the Uniform Tire Quality Grade Standards (UTQG). This test informs customers on what sort of treadwear a tire may provide, and the score for a graded tire can be found on its sidewall, on its retail sticker, or in the details listed for the tire online.
The treadwear score will be the three-digit number in sequence, such as 600 A A. A tire that scores 200 can be expected to wear twice as well as the UTQG test’s control tire, known as a Course Monitoring Tire (CMT). The scores are a projection of how long they’ll likely last. But the variables of the real world can cause a tire with a 300 rating and a 700 rating to last an equal amount of time.
According to Consumer Reports testing the Pirelli P4 Four Seasons Plus—was estimated to last as long as 100,000 miles of highway driving. If you only have to buy one set of tires for the lifetime of your vehicle, that’s money well spent. But the way to get the most from whichever tires you buy is to maintain them properly.
How to Determine Tire Tread Life
To determine when your tires’ tread life is up, you can perform what’s called the penny test. Hold a penny with Abe’s head down and place it between the vertical grooves of your tires. If the crown of his head disappears, the tread on your tires is good. However, if the top of Abe’s head appears, it’s time for replacements.
Also be aware that your tires may need replacing well before their tread gets worn away. Even tires stored in a dry, temperate garage can develop cracks that can form in the tread and/or sidewall areas thus affecting the integrity of the construction. For this reason many tire manufacturers recommend replacing tires older than six years. Also, many garages will not service tires older than 10.
To check the manufacturing date of your tires, just look on their sidewall for an identification number that begins with the letters DOT, for Department of Transportation. The last four digits tell you the week and year the tire was manufactured. A tire with a DOT number ending in 3517 were made in the 35th week of the year 2017.
You may second-guess replacing a set of tires that still has decent tread on them just because they’re more than six years old. But tread life is only part of what makes a tire safe.