Why tyre size, rolling circumference and tread differences matter on Subaru AWD vehicles, especially when replacing only one or two tyres.
AWD systems compare wheel speeds
Large differences in rolling circumference can make the driveline work harder and may affect AWD behaviour.
Measure the other tyres
Remaining tread depth, tyre model, size and condition help determine whether a single tyre replacement is sensible.
Fix the cause of uneven wear
Before fitting new tyres, check alignment and suspension condition if edge wear or irregular wear is present.
Need your Subaru assessed?
If a symptom is already present, a workshop inspection is more useful than trying to diagnose the vehicle from a generic guide. Vehicle condition, engine/transmission type and fault data can change the answer.