You’ve spent a few years and thousands of miles with your car, and you’ve finally approached that big moment: The original tires that came on your car are now worn out. The first questions that come to mind are, “What should I buy?" and "Do I stick with the same tires, or try a different model or brand?”

Research by Consumer Reports shows most car owners buy—or attempt to buy—the same tire that came on their vehicle, either solely for convenience, or to preserve or get back that new-car feel. Owners of older and previously owned cars tend to switch tire models, often seeking either a low price or better tread life or performance.

Tires that come on new cars—original equipment tires—are designed in a collaboration between the tire and vehicle manufacturers to ensure the shod rubber complements the ride and handling sought for the vehicle. Emphasis on quietness and fuel efficiency are usually high priorities for many original equipment tires. Matching the appropriate tire traits translates to better owner satisfaction—so it’s a big deal for car makers that the tire suits the vehicle.

A shop can handle installing tire replacements for your car

Original equipment tires are available for replacement, so technically they can also be called replacement tires. However, traditional replacement tires are not designed for any one car, and tend to be designed with an emphasis on treadwear and all-weather grip (if it’s an all-season tire).

How hard is it buy an original equipment tire? The simple answer: It depends on what car you drive and what tire you need.  

The challenge lies in identifying the original equipment tire on your car. Some vehicle manufacturers make it very easy, but others much less so—or nearly impossible. General Motors offers one of the best identifiers, a TPC (Tire Performance Criteria) spec number embossed on the sidewall of the tire (shown below), indicating it meets GM's specifications. To get a direct replacement, make sure the new tire matches the TPC number of your original tires.

TPC spec embossed on tire sidewall.
General Motors vehicles, like this Cadillac, use original equipment tires that have the TPC spec number embossed on the sidewall.

Some other vehicle manufacturers use codes or symbols embossed on the sidewall of the tires. BMW and Mini use a star; Mercedes uses MO or MO1 or MOE; Jaguar uses J; and Porsche uses N and a number system. These indicators are not very intuitive, and placement and size of the code vary.

But it’s better than the alternative, as many vehicle manufacturers rely on tire product codes to identify original equipment tires. The product code might be found in tire manufacturer literature or on a company's website—and often the tire will be listed for original equipment fitment for a specific car. Your tire dealer should be able to help.

A secondary source for verification is TireRack, which offers the original equipment tire models that come on many new cars. Some other tire-sales websites might do so, too. Finally, check your car's owner’s manual, which often provides guidance on replacing tires.

Since original equipment tires are made for specific cars, you might need to special order them. This can be a slow process, particularly if you need an uncommon tire size or have a low-volume vehicle.

In the end, whether you have the original equipment or replacement tires on your car, a good tire tip to follow is to rotate your tires routinely for optimum tread life. When you need to replace them, install a complete set of four new tires for the best balance of handling and ride.