The size of your tires has a direct impact on performance and safety, which is why it’s always best to stick with the manufacturer’s recommended specs. Choosing the wrong size can lead to problems you might not expect.
If you go with a smaller tire to try to improve fuel economy or acceleration, you could end up damaging the wheels. It can also throw off your speedometer readings and affect how the braking system behaves, since the actual speed won’t match what the car thinks you’re doing.
On the flip side, putting on larger tires increases the overall diameter, which puts extra stress on the suspension and wheels. This can reduce shock absorption and make the ride harsher.
The safest choice is always to use tires that match your car’s specs. The markings on the tire sidewall tell you everything you need to know—diameter, load capacity, speed rating—and once you understand those, it’s much easier to choose replacements that won’t cause problems. Driving habits also play a big role; smoother driving extends tire life.
And while you can look up factory specs by vehicle model, the most accurate way is to check the tires currently mounted on your car, since wheel sizes can vary depending on trim level or even dealer-installed options.
How to Read Tire Information
1. Manufacturing Date
Look for the letters DOT on the sidewall. At the end, you’ll see a four-digit code. The first two numbers show the week of the year, and the last two show the year. For example, “2620” means the tire was made in the 26th week of 2020 (late June).
Even if your tires look fine, they should generally be replaced once they’re more than five years old. Rubber ages, and old tires can fail suddenly.
2. Tire Size, Load, and Speed Rating
Take something like 245/40R19 98Y:
- 245 → the tire width in millimeters.
- 40 → the aspect ratio (height of the sidewall as a % of the width). Lower numbers mean better cornering, but also a stiffer ride and more risk of rim damage on rough roads.
- R19 → radial construction, 19-inch wheel diameter. Almost all modern tires are radial, which handle high speeds and cornering better than old-style bias-ply tires.
- 98 → load index, which here means each tire can carry about 750 kg.
- Y → speed rating, meaning it can safely handle speeds up to 300 km/h under full load.
3. Proper Air Pressure
On the sidewall you’ll also see the maximum load and maximum pressure. For example, a tire might say it supports up to 800 kg at 50 psi. But you should never inflate to the max—around 80% of that number is the safe target.
Too much air means the center wears out faster. Too little air makes the edges wear down, hurts fuel economy, and can even damage the internal structure. Keeping your tires at the right pressure is one of the easiest ways to extend their life.
