All Wheel Drive and Tires: Do You Need to Replace All Four?
Owners of all wheel drive vehicles often hear that all four tires should be replaced together. This overview explains the reasoning behind that common guidance.
All wheel drive (AWD) and four wheel drive systems send power to more than one axle. Many vehicle and tire manufacturers publish guidance that tires on these vehicles should be closely matched in tread depth. The explanation below is general and should be confirmed against your own vehicle owner manual.
Why Matched Tread Depth Matters
A tire with less tread has a slightly smaller rolling diameter, so it turns a little faster than a deeper tire. On an AWD vehicle, large differences in rolling diameter can make the drivetrain work to compensate. Several manufacturers state that this extra effort can add load to AWD components over time. The exact tolerance varies by manufacturer and is listed in the owner manual.
Common Scenarios
- One tire damaged on a newer set. If the other three still have most of their tread, some shops can shave a single new tire to match where the manufacturer permits it. Otherwise replacing in pairs or as a full set may be recommended.
- Tires already partly worn. When the existing tires are well into their life, replacing all four keeps rolling diameters close and is often the simpler choice.
- Two tires worn. When only two need replacing, the new pair is typically installed on the rear axle for stability, subject to manufacturer guidance.
Front Wheel and Rear Wheel Drive
Vehicles with a single driven axle are generally more tolerant of small tread differences than AWD vehicles. Even so, keeping tread depths reasonably balanced supports even handling and predictable braking.
Because tolerances differ between vehicles, the most reliable step is to check the AWD tire guidance in your owner manual and discuss your specific situation with a qualified tire professional.