Symptoms
- One or two tires are a different size or significantly more worn than the others
- AWD warning light appeared after a tire replacement
- Manufacturer specifies matching tread depth across all four tires
Likely causes
- CommonOnly one or two tires replaced instead of a full setAWD systems are sensitive to even small rolling-diameter differences between tires.
- PossibleDifferent tire brand or model with a slightly different actual diameter despite the same size labelManufacturing tolerances mean two tires labeled the same size can differ slightly in actual diameter.
What to do
- Check your owner's manual for the manufacturer's tire matching requirement, often within 2/32 inch tread depth or a percentage of circumference.
- Measure tread depth on all four tires with a gauge.
- If tires are mismatched beyond the allowed tolerance, plan to replace as a full set rather than individually.
- Avoid driving long distances or at highway speed with significantly mismatched tires on AWD, since it can damage the transfer case or differential.
- Consult a dealer or tire shop familiar with your specific AWD system if you're unsure of the tolerance.
Tools and parts
- Tread depth gauge
Matching set of four tiresSearch: “tire size for [your car model]”
When to call a pro
If you're unsure whether your tire mismatch is within tolerance, a dealer familiar with your AWD system can advise, since tolerances vary by manufacturer.
Safety
Use caution
Continuing to drive an AWD vehicle with significantly mismatched tires can cause expensive drivetrain damage; address it before long trips.