Tires are the only part of the car that touches the road. Braking, cornering, comfort, noise and fuel economy all depend on them, so it is worth choosing them carefully instead of buying whatever is cheapest.
Read the sidewall
A typical tire size looks like 225/45 R17 94V:
- 225 is the width in millimeters;
- 45 is the aspect ratio, the sidewall height as a percentage of the width;
- R means radial construction;
- 17 is the wheel diameter in inches;
- 94 is the load index and V the speed rating.
Use the size, load index and speed rating listed on the sticker inside your driver’s door or in the owner’s manual. The four-digit DOT date code shows when the tire was made: “2324” means week 23 of 2024.
Choose the type for your climate
All-season tires are a compromise that works for most drivers in mild climates. Winter tires, marked with the three-peak mountain snowflake symbol, grip far better on snow, ice and cold roads. All-weather tires also carry the snowflake symbol and suit areas with occasional snow. Summer tires give the best grip and braking in warm conditions but are unsafe in cold weather. All-terrain tires suit trucks and SUVs that leave the pavement.
Compare beyond the price
Independent tests by consumer magazines and automobile clubs compare braking distances, wet grip, noise and wear. In the US, tires also carry UTQG ratings for treadwear, traction and temperature, which are useful for comparing tires of the same brand. In Europe, the tire label shows fuel efficiency, wet grip and noise. A tire that brakes a few meters shorter in the wet is worth paying a bit more for.
When to replace them
In the US, tires are legally worn at 2/32 inch of tread, and tread-wear bars appear across the grooves at that point. Many experts advise replacing them sooner, at 4/32 inch, because wet braking gets much worse as tread wears down. The old “penny test” checks for 2/32; a quarter checks for 4/32. NHTSA’s tire safety page explains these checks.
Age matters too. Rubber hardens over time, and many manufacturers recommend replacement after six to ten years regardless of tread. Replace tires in pairs (ideally all four on AWD cars), and put the newer pair on the rear axle.
Look after them
Check pressure monthly, rotate tires as recommended and have the alignment checked if the car pulls or tires wear unevenly. Our guides on what to do with a puncture and driving on a spare cover emergencies, and winter cars and tires explains why tires matter more than AWD in snow.
