Why You Should Always Replace All Four Tires on an AWD System

How AWD Systems Require Matched Tires

All-wheel-drive vehicles send power to all four wheels simultaneously. The system assumes all four tires have the same diameter. Even a small difference causes the drivetrain to constantly adjust power distribution. This generates heat and stress. New tires have full tread. Used tires have worn tread with smaller diameters. The mismatch forces the drivetrain to work continuously to compensate.

The Cost of Ignoring This Rule

Replacing only two tires on an AWD vehicle can damage the differential or transfer case. These components cost $1,500 to $3,000 or more to repair. The money saved by replacing only two tires becomes trivial compared to the repair cost. Replacing all four tires upfront prevents expensive damage.

Tire Diameter Differences Matter

A tire's diameter decreases as tread wears. A new tire with 10/32 tread has a larger diameter than a worn tire with 5/32 tread. The difference might be only 0.5 inches, but it's significant to the drivetrain. When two tires are new and two are worn, the diameter mismatch stresses the differential continuously.

AWD Tire Replacement Rules

• Replace all four tires at the same time if all have similar wear
• Replace all four if any tire is damaged or punctured
• Never replace only two tires on an AWD vehicle
• If only two tires are damaged, replace all four for safety and drivetrain protection
• Consider tire rotation every 8,000 km to maintain even wear

The Exception: Emergency Repairs

If a tire is punctured and you need temporary repair, a plug or patch is acceptable short-term. However, get a full replacement as soon as possible. Don't drive extended distances on a temporary repair. Plan to replace all four tires within a few days.

FWD and RWD Vehicles: Different Rules

Front-wheel-drive vehicles can tolerate replacing two tires. Rear-wheel-drive vehicles can also replace two tires. However, all-wheel-drive vehicles are different. The continuous power to all four wheels makes matching tire diameter critical. This is one of the unique maintenance requirements of AWD ownership.

Budgeting for AWD Tire Replacement

Budget for all four tires at once. A set of four mid-range tires costs $400 to $800. While this is more expensive than replacing two tires, it's far cheaper than differential repair. Spread the cost by replacing tires when wear indicates it's necessary, not before.

Frequently Asked Questions