For FWD and RWD cars, replacing in pairs is fine if the other two have life left. For AWD, you usually need all four to keep tread depths matched. Here is the decision tree and why AWD is different.
AWD systems (Subaru, Audi, BMW xDrive, etc.) require tread depths within 2/32 inch across all four tires. A mismatched tire makes the differential or coupler work harder, leading to expensive damage.
Replace 2 tires on the same axle when the others have 5/32+ tread left. Put the new tires on the rear (better wet stability) regardless of which axle drives.
Counterintuitive but proven: new tires on rear, even on FWD. Rear with more grip prevents oversteer in wet emergencies. All tire makers and NHTSA say this.
If only 1-2 tires are damaged and 2 others have only 4-5k miles, some shops will shave new tires to match. $25-$50 per tire shaved.
Acceptable when the other 3 tires are nearly new (less than 25% worn). Otherwise the differential difference is too large.
| Situation | Recommendation |
|---|---|
| FWD, other 2 tires <25% worn | Replace just the bad ones (or all 4 if cheap) |
| FWD, other 2 tires >50% worn | Replace all 4 |
| AWD, other tires <2/32" difference | OK to replace pair - put new ones on rear |
| AWD, other tires >2/32" difference | Replace all 4 (mandatory for most AWD) |
| Damaged tire, others nearly new | Replace just that 1 (1-2 weeks old others) |
| Bald tires all around | Replace all 4 for consistent grip |
Tell us your car (especially if AWD), what failed, and the other tires' tread - we'll tell you 2 or 4.
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Only if the other 3 tires are nearly new (less than 2/32 inch tread difference from the new one). Otherwise the differential will be forced to work harder and can fail expensively. Better to replace all 4.
Always on the rear, regardless of drive type. New tires on the rear prevent oversteer in wet braking emergencies. Confirmed by NHTSA, Michelin, and every major tire maker.
On FWD/RWD: same brand across an axle is required (front pair or rear pair must match). Mixing front to rear is OK. On AWD: same brand and model across all 4 is strongly recommended.
A shop machines a new tire down to match the worn ones. $25-$50 per tire. Used when you damage 1-2 tires on a low-mileage AWD set. Better than buying 4 new tires.
Within 2/32 inch is the common spec. Subaru is stricter at 1/32. Check your owner's manual - some AWD systems are more forgiving than others.
Yes, but put the new ones on the rear and rotate the better-treaded fronts to match. Plan to replace the other 2 within 5000-10000 miles.