Automotive Maintenance

Buying a used car? Check the tires for these 6 things

A worn tire on a car

Buyers have lots of things to look out for when considering a used car, and tires are one of them.

While most shoppers focus on service history and odometer mileage, tires are a critical component of reliability and safety. Unlike tires on new cars, the tires on used cars can be anywhere in their life cycle, from brand new to dangerously worn down. And since a full set of tires can cost hundreds of dollars, knowing whether a car will need new tires soon can also factor in to whether it's a good deal.

The DOT number on a tire's sidewall

The numbers 0820 on the sidewall of this tire indicate that it was made in week 8 of the year 2020.

1. Check the age of the tires

The first thing you'll want to know is how old the tires are. Rubber loses flexibility over time, putting older tires at increased risk of a sudden failure even if they don't look worn down.

Check with the manufacturer for their recommended replacement age, usually somewhere between 6 and 10 years. If the tires are older than 6 years, you should have them inspected by a professional at least once a year.

To determine a tire's age, look around the rim of the tire near the wheel until you find the letters DOT, followed by letters and numbers, including 4 digits inside an oval shape. Those 4 digits tell you the week and the year that the tire was made, with the week indicated by the first 2 numbers and the year indicated by the second 2. For example, 4016 would indicate the tire was made in the 40th week of the year 2016, or October 2016.

2. Check the tires' tread depth

Another crucial thing to check is the remaining tread depth. Depth is measured in 32nds of an inch, with most new tires starting out at 10/32” or 11/32” and wearing down as they're driven. Driving on tires with less than 2/32” of tread is unsafe (as well as illegal in most states), but performance begins to suffer earlier. AAA recommends replacing tires when they reach 4/32" of remaining tread.

The easiest and most accurate way to check tread depth is with a dedicated tire gauge, available at auto parts stores. But if you have spare change handy, you can also use a quarter or penny to measure depth.

RELATED: Learn how to measure tread depth with a penny or quarter, and why AAA recommends replacing tires at 4/32" of tread

If you find that the tires on a used car are worn down and need replacement, or are close to it, keep that in mind when considering the price.

An old car tire with an unevenly worn tread

This tire has worn down unevenly on one side; note the lack of horizontal tread grooves on the right. This is probably an indicator of a misaligned wheel.

3. Check for uneven tread wear

The tires on a properly maintained car will wear evenly on each part of the tread, and evenly across the set of 4 tires. Even wear ensures ride comfort and allows all the tires to be replaced at the same time. By contrast, unevenly worn tires can mean noisy or uncomfortable driving, and may need to be replaced early in piecemeal fashion.

Briefly check the used car's tires for signs of irregular wear. This includes a side of the tread being more worn down than the other, as might happen with a misaligned wheel; or "cupped" tires with circular smooth spots, the result of a worn-out suspension. Not only can these be warning signs that the tires will need early replacement, they can also point to underlying mechanical issues.

RELATED: Learn more about identifying irregular tire wear

4. Check sidewalls for damage or cracking

After looking at the treads, inspect the sidewalls for large scrapes, cracks, bulges, or missing rubber. Pay special attention to any long grooves that curve along the length of the tire, as this can indicate that long-term underinflation has pinched the rubber and worn through the sidewall. A tire with any of these, or anything other than very superficial scratches and wear, is not safe to drive on. When in doubt, have the tires professionally inspected.

Damage to the sidewall can lead to sudden blowouts, so such tires need immediate replacement—an added expense if you buy the car they're on.

A finger points to the tire size and speed/load ratings on the sidewall of a car tire

The first sequence of numbers and letters on this tire's sidewall lists its size (205mm wide, 55% of that in height, for 16-inch rims). The second sequence shows it has a load index of 91 and a speed rating of V.

5. Check the sizes and speed/load ratings

Once you've determined the condition of the tires, you'll want to make sure they're right for the car. That means checking that they match the car's required size and have the correct load index and speed rating.

The tire size will be a sequence of numbers and letters, such as P225/60R17. In order, these indicate:

  • the type (P for passenger tires)
  • the width (225 millimeters)
  • the height (60% of the width)
  • the construction (R for radial)
  • the diameter of the wheel rim (17 inches). 


Find the size on each tire's sidewall and check it against the car's required tire size, which you can usually find in the owner’s manual, driver-side door jamb, or gas door. Most cars require the same size tire for all 4 wheels, though a few have a "staggered fitment," with larger wheels in the front or back.

Then check the car's required speed and load ratings. You'll also find these on the tire’s sidewall with a short sequence right after the size, such as 98H. The number is the load index and indicates how much weight the tire can bear, while the letter is the speed rating and specifies the maximum speed the tire can handle. 

Make sure both these ratings meet the requirements of the car—exceeding them is OK, but falling short is not. For example, if a car calls for 96U tires, it would be safe to mount 98V tires, but not 89V ones.

6. Check the type & model of tire

There are many different types of tires, with some focused on low noise and comfort, others designed for maximum grip and handling, and still others optimized for wet weather or cold conditions. Do a little research and see if the tires on the used car you're considering will fit your needs.

While this is unlikely to make or break a deal, it can help you pick a winner if you're looking at many similar cars.

RELATED: A tire-buyer's guide to the different types of tires

A wheel being unbolted from a car at a mechanic shop

Need new tires, an inspection, or rotation?

If you need new tires or another tire-related service, consider a AAA Approved Repair shop. These shops are regularly inspected by AAA and come with member benefits.
 

Today, there are about 7,000 AAA Approved Repair facilities in the U.S. and Canada. 

Discount Tire logo

Looking for a used car dealer you can trust?

AAA members can enjoy a great car buying experience with AAA Car Buying Service. Find the used car you want from a certified dealer and feel confident in the price you’re paying.

AAA Car Buying Service is only available to AAA members. Outside of Southern California, AAA Car Buying Service is managed by TrueCar, Inc. Only car buying research tools are available in Hawai‘i.

AAA members save with Discount Tire

AAA members get exclusive savings at Discount Tire and America’s Tire: Up to $40 off a set of new “better” or “best” tires, or a free tire repair (a $20 value).1 Buy a set of tires and you’ll get free air checks, tire inspections, tire repairs, rotation, and re-balancing. 

Offer is only available to AAA members in Southern California, New Mexico, Tidewater Virginia, and the Kansas City metro area. 

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