Is it Okay to Mix Tires?

In a word: No. It is not okay to mix tires. Your tires are the most important safety component on your car. They’re the only contact between your ride and the road, which is why it’s important not to compromise their performance.

There are some things that are more critical than others, though. Mixing your tires could mean different things, so let’s address all of them:

Is it Okay to Mix Tire Sizes?

No. The only exception to this is some sports cars that have different size wheels front and rear. In this case you’ll have no choice. You need to select a tire that fits your rim and use it consistently on all four wheels.

A tire size from left to right shows the width, the aspect ratio, and the rim size. For example, a 215/55 16 tire has a width of 215mm. The “55” means that the tire height is 55% of 215, or 118 mm tall, and the rim is 16 inches. A 215/75 16 tire will fit on the same rim, but it will be a different total diameter than the 215/55. That difference, while small, is enough to throw out the handling and balance. It can even cause premature wear on drivetrain and steering components.

Is it Okay to Mix Tire Brands?

This part is less critical, but the answer is still no. That’s because different brands use different compounds and different construction, so the grip is inconsistent across your vehicle. The same is true of tire types, for example mixing winters and all-seasons. When the grip is inconsistent you get uneven performance when cornering, but even more critically: uneven stopping power.

What if I Have to Mix Tire Brands?

Even the best-laid plans come undone from time to time. In emergencies, like when you damage a tire in a rural area and replacements aren’t available you might have to mix tires. In this instance, you need to make sure you:

1. Replace them in pairs
   Make sure you do either both front tires, or both rears. Difference left-to-right have a bigger impact than differences front-to-rear.
2. Match the sizes
   This remains critical. Carefully match the width, aspect ratio as well as the rim size.
3. Match the load capacity and speed rating
   The numbers and letters after the size stamped on your sidewall are the load capacity and speed rating. These numbers should be the same on four corners of your car. They speak to the durability and construction of your rubber.
4. Match the type
   If you’re replacing a winter tire, replace it with another.

Should You Put New Tires on the Front or Back?

By now we’ve covered why you shouldn’t mix rubber left-to-right, but if you do have to replace only two tires, do you put the new ones on the front, or back?

This one generates lots of debate on the internet, but let’s put it this way: Your front tires handle most of the braking and steering duties of your car. The fronts provide stopping grip and steering traction. For that reason, I advocate putting newer rubber on the front.

Almost all modern cars are front-wheel drive, with all-wheel drive systems powering the front wheels most of the time. That means these are the hardest working and most relied-on wheels.

Trucks and sports cars are more likely to be rear-wheel drive, and in those cases you’ll need to consider if you want traction for acceleration or prefer to put your best foot forward when braking or steering.

I know which one I’d choose: Best rubber up front, please.

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