Before you can buy a tire, you need to know exactly which size your vehicle takes. There are three reliable ways to find this out, and they should all agree. If they don't, something has been changed on your car.
Method 1 — Read your current sidewall
The fastest way. Walk out to your car, look at any one of the tires currently on it, and read the size string off the sidewall. It will look something like P225/45R17 92H. Write it down exactly.
Caveat: this only works if the previous owner — or you — didn't put non-standard tires on the car. About one in eight used vehicles we see has been fitted with a size the factory never installed.
Method 2 — Driver's door jamb sticker
Open the driver's door and look at the edge of the door or the door jamb. Almost every car sold in the U.S. since 2003 has a yellow-and-white sticker that lists the original equipment (OE) tire size and the correct cold inflation pressure. This is the factory-recommended size. If your sidewall and the door sticker disagree, the door sticker wins.
Method 3 — Year / make / model lookup
If you don't have the car in front of you, every reputable tire retailer has a vehicle lookup that will tell you which sizes are correct for your trim. This matters because base trims and sport trims of the same car often take different sizes.
Reading the size string
A size like 225/45R17 92H decodes as: 225 millimeters wide; aspect ratio of 45 (sidewall is 45% of width); R for radial construction; 17-inch wheel diameter; load index 92; speed rating H. All of these matter and you should replace with the same numbers — though the load index and speed rating can usually go up, never down.
Can I change sizes?
Yes, within limits. You can run a tire whose overall diameter is within 3% of the original, with the same load rating or higher. This is called a 'plus' or 'minus' size. Go too far and your speedometer reads incorrectly, your ABS gets confused, and you may rub the fender on a turn.
If you're not sure, send us a photo of your door jamb sticker. We'll tell you exactly what fits — at no obligation.