Safety · guide

When to replace your tires

By TireMileageLast updated 2026-10-255 sources citedHow we work

1. Tread depth: 2/32 inch

NHTSA: “Tires are not safe and should be replaced when the tread is worn down to 2/32 of an inch,” and it recommends checking tread at least monthly. Two checks (NHTSA, TIA, USTMA):

• Wear bars: small raised rubber humps molded into the main grooves at 2/32 inch. When the tread is level with them, replace the tire.
• Penny test: place a penny upside down in a major groove with Lincoln’s head facing you. If you can see the top of his head, replace the tire (NHTSA). TIA says to check at any point in any major groove and then see a tire professional.

Continental’s mileage warranty counts a tire as worn out at the same point, 2/32 inch (1.6 mm) (Continental); the cost-per-mile math uses the same endpoint.

2. Damage and irregular wear

Per TIA: if any steel or fabric is visible, replace the tire immediately; have a professional look at bulges, irregular wear or anything abnormal. NHTSA adds that you should stop using tires with cuts, cracks or bulges, or irregular wear from underinflation or overloading, and take note of changes in noise or vibration. Don’t use a full-size spare as a replacement for worn tires except in an emergency.

3. Age

“As tires age, they are more prone to failure. Some vehicle and tire manufacturers recommend replacing tires that are six to 10 years old, regardless of treadwear,” says NHTSA, which also says you cannot detect aging by looking. It is a greater concern for low-mileage vehicles, recreational vehicles and spares, and in the southern Sun Belt (NHTSA). Some warranties set their own limit: Continental’s does not cover tires in service longer than 72 months (Continental).

Find the tire’s date code

On the sidewall, after “DOT”, the last four digits of the Tire Identification Number are the week and year. NHTSA’s example: 0308 = third week of 2008. The regulation’s example: 0109 = week beginning Sunday, Jan. 4, 2009 (49 CFR 574.5). The TIN may be on only one side of the tire. More in how to read a tire sidewall.

4. Replacing fewer than four

• TIA’s best practice is to replace all four at once; some all-wheel-drive and four-wheel-drive vehicles require it so the drivetrain isn’t damaged.
• One new tire: mount it on the rear axle, paired with the tire with the most tread. Two: install the new ones on the rear, or the vehicle may be more likely to lose control when turning in wet or slippery conditions (TIA).
• Match the size, load index and speed rating on the placard (sidewall guide).

Choosing replacements

Compare candidates for your size on a size page, for example 225/65R17, 215/65R16 or 265/70R17, and see how to find long-lasting tires. Help the next set last with rotation, pressure and alignment.

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