Having two different-sized tires on the same axle is generally not a good thing. If the diameter of the two tires is close, then the rolling radius is about the same, so in the short term, you probably won’t have any damage, but long term, you run the risk of messing up your car’s differential.
To mix or not to mix your tires?
In this section, you’ll learn the critical information about mixing tires on your vehicle. Primarily, you should avoid mixing different tire brands and different tread patterns. There are rare exceptions for approved mixed-tire fittings, but in general, manufacturers do not recommend tire mixing at all.
For optimal safety and performance, Continental recommends fitting the same tires to every wheel position on your car, so drivers should have the same brand, size, tread pattern, load index, and speed rating on the front and rear tires.
As a bare minimum, tires must conform to recommendations concerning size, load index, and speed rating as provided by the vehicle manufacturer. It’s a legal requirement in many countries.
Driving a car with a set of mismatched tire sizes, constructions, load indexes, or speed ratings can pose a danger to you and other road users. It’s always best to follow the vehicle manufacturer’s specifications or consult a qualified tire specialist.
The benefits of tire rotation
Rotating tires is a proven strategy to maximize tire service life and tire wear.
The vehicle manufacturer will have custom guidance for the optimal rotation pattern and frequency. The rotation pattern depends on whether you have symmetrical, asymmetrical, or directional tires. If there are no special considerations, our recommendation is to rotate the wheels axle-wise between the front and the back on a regular basis.
Alternatively, tire rotation at mileage intervals between 5,000 km and 10,000 km is also effective.
If you notice signs of uneven tire wear, however, consider rotating them even more frequently. And ask your friendly neighborhood tire dealer to check for any wheel misalignment or other mechanical problem. They can make the necessary corrections.
Speaking of air pressure you should also adjust the air pressure according to the vehicle manufacturer’s recommendation for the new wheel position, as the specific pressures for the front tires and rear tires may differ.