Drivers should avoid mixing tires with different tread patterns, internal constructions or sizes and use identical tires on all of their vehicle's wheel positions in order to maintain the best control and stability. Additionally, drivers should never mix winter tires with all-season/summer tires or mix run-flat tires with non-run-flat tires.
Unfortunately wearing out all tires at the same time isn't always possible. Sometimes vehicle design, the use of differently sized tires on front and rear axles, insufficient maintenance and/or driving conditions conspire to prevent it from happening.
The first recommendation is to always keep the same level of grip all the way around the car. To do this simply choose the exact same tire as the others on your vehicle.
Or, choose equivalent tires from the same tire performance category that share the same speed rating, handling and traction characteristics of the original tires. While this isn't as desirable as selecting the exact tire currently on the vehicle, it can become necessary when the original tires are no longer available.