Do All 4 Tires Need To Match On An All-Wheel Drive?

"Using "matched" tires means all four tires are the same brand, design and tread depth. Mixing tire brands, tread designs and tread depths may cause components in the vehicle's driveline to fail." 

The ability of a four-wheel drive and all-wheel drive vehicles to divide the engine's horsepower between its four tires is especially useful on loose or slippery surfaces such as sand and dirt, as well as on wet, icy or snow-covered roads. However it's important to remember that in order to transfer this extra power, the four-wheel drive and all-wheel drive vehicle's driveline mechanically connects the tires so they work in unison. 

This necessitates that four-wheel drive and all-wheel drive vehicles use tires that are very closely matched. This is because different diameter tires roll a different number of times each mile as a result of the variations in their circumferences. Tire diameter variations can be caused by accidentally using different sized tires, tires with different tread designs, tires made by different manufacturers, different inflation pressures or even tires worn to different tread depths.

As an example of different tire diameters resulting from tires worn to different tread depths, we'll compare two 225/45R17-sized tires, a new tire with its original tread depth of 10/32-inch and a second tire worn to 8/32-inch of remaining tread depth. The new 225/45R17-sized tire has a calculated diameter of 24.97", a circumference of 78.44" and will roll 835 times each mile. The same tire worn to 8/32-inch of remaining tread depth is calculated to be 1/8" shorter with a diameter of 24.84", have a circumference of 78.04" and will roll 839 times per mile. While the difference of 1/8" in overall diameter doesn't seem excessive, the resulting 4 revolutions per mile difference can place a continuous strain on the tires and vehicle's driveline. Obviously, the greater the difference in the tires' circumferences, the greater the resulting strain.

This makes maintaining the vehicle manufacturer's recommended tire inflation pressures and using "matched" tires on all wheel positions necessary procedures to reduce strain on the vehicle's driveline. Using "matched" tires means all four tires are the same brand, design and tread depth. Mixing tire brands, tread designs and tread depths may cause components in the vehicle's driveline to fail.

Mismatched tires or using improper inflation pressures for all-wheel drive and four-wheel drive vehicles can also result in immediate drivability problems. Some Control Trac equipped vehicles in 4Auto mode may exhibit a shutter on acceleration and/or a noise from the front driveline and transfer case while driving. Some all-wheel drive and four-wheel drive vehicles may exhibit axle windup or binding while driving. Some four-wheel drive vehicles (manual or electronic shift) with a two-wheel drive mode may refuse to shift "on the fly" into 4x4 Auto or 4x4 High at highway speeds.

There are several suggestions that have been offered to drivers who are replacing pairs or individual tires on their four-wheel drive and all-wheel drive vehicles. Some vehicle manufacturers recommend that all tires maintain the same rolling radius and circumference, while others suggest that all tire circumferences remain within 1/4- to 1/2-inch of each other. Other vehicle manufacturers recommend that all four tires remain within 2/32-, 3/32- or 4/32-inch of each other, or within 30% of each other in relative remaining tread depth.

Regardless of the vehicle manufacturer's recommendations, the least stressful application is when all four tires are the same tire brand, tread design and equivalent tread depth.

Before buying pairs or individual tires for all-wheel drive and four-wheel drive vehicles, drivers should read their vehicle's owners manual or contact the vehicle's manufacture dealer's service department for confirmation of their specific vehicle's requirements.