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How to Inspect Tires When Buying a Used Car

Ideally, when you’re kicking the tires on a possible used-vehicle purchase, you should get the candidate inspected by a mechanic. If you can’t, there are still some things anyone can watch out for, and that includes the tires themselves.

Tires play a key role in keeping your vehicle safe on the road. They can also be relatively expensive to replace: Buying four new tires for a typical pre-owned compact SUV can easily set you back more than $500. And if you need them before your used vehicle is drivable, it’s like adding that amount directly to the purchase price. Of course, you can also take advantage of the tire situation as a negotiating point, but what’s important in either case is understanding how to evaluate tires when buying a used car.

Are the Tires the Right Size?

A good starting place is to verify the size of the tires, especially considering how popular oversized wheels and tires have become on the aftermarket. These may look pretty slick, but even if they’re in perfect condition, tires that are too big for a given vehicle will diminish its performance and fuel economy. Also, some sellers may not be overly careful when changing their tires, and they may end up replacing an existing flat without following manufacturer guidelines.

The thing is, checking those guidelines is exceedingly simple, with most national and local tire-store chains providing vehicle-search functions on their websites. All you need to do is enter some basic information about the vehicle – like its make, model and model year – and you’ll get results showing the proper size tire and information about how much new ones will cost. You also can find manufacturer tire recommendations the old-school way, by checking the vehicle’s owner’s manual. In most cars and trucks, tire-size information is also found on the driver’s side door jamb, in the glovebox and/or on the inside of the fuel-filler door.

Tires typically have their sizes printed right on their side walls, making comparisons quick and easy. As a practical matter, tires carry a lot of information, but for size purposes, you should focus on a series of letters and numbers such as P225/65R17. Here, the first letter indicates the tire was meant for a passenger vehicle, the indicates a radial construction, and the numbers represent tire width in millimeters, a height-to-width ratio, and wheel diameter in inches.

Are They in Good Condition?

As you’re looking at the tires for their sizes, take time to make a careful visual inspection of the sidewalls and treads. Any physical imperfections to the former, like cracks and blisters, are a sign that a tire needs replacing. As for the treads, there are two common ways to see if it’s time for new rubber. First, many tire-makers incorporate wear bars that will become visible between the treads when a new tire is necessary. An alternative is the penny test. If you put a penny head-down between the treads, at least part of Lincoln’s head should be covered. Otherwise, that tire should be replaced.

You also should pay attention to uneven tire wear, as that can be a sign of more serious trouble with a vehicle’s suspension or steering. Other essential checkpoints are the valve stems, and along with inspecting those, you should use them to verify each tire’s inflation pressure. Proper recommendations for that are shown on the tire sidewalls as well, and so is the data you need to tell how old a tire is.

That can be a particular issue with older used vehicles that may be riding on their original tires. Now, there’s no hard-and-fast rule about how long tires can last chronologically, but major manufacturers like Michelin cap their lifetimes at 10 years, “even if they appear to be in usable condition.”

To find out when a tire was manufactured, search for the string of letters and numbers that begins with DOT. This is a tire identification number that’s required by the U.S. Department of Transportation, and the final four numbers include two that represent the week and two that represent the year during which the tire was made. All tires manufactured since 2000 must have this number, while those that don’t would be too old to keep anyway.

Some Final Thoughts

Our last words of wisdom include a reminder about the tire-replacement multiplier effect: Most automakers recommend that, for two-wheel-drive vehicles, if you have to change one tire, you also should change the other one on the same axle to maintain even tire wear. With four-wheel-drive vehicles, all four tires should be replaced at the same time and for the same reason. Needless to say, this also multiplies your costs.

Nor should you forget about the spare tire. If it’s not up to par, that’s a further financial outlay to weigh in the balance.

Does all this mean you should avoid a used vehicle with possible tire issues? Not necessarily, but it means you should pay a little less if you buy one.

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