I often hear from customers who have damaged one tire on their AWD vehicle that they would like to buy one tire to replace the damaged tire.
Simply installing one new tire runs the risk of drivability problems or expensive drive line damage. I recommend they consider a set of four depending on availability and the tread depth of the three remaining tires. But replacing the other three partially worn tires along with the damaged tire does increase the cost. Another option to consider is shaving the new tire to the current tread depth of the tires that remain on the vehicle.
By matching the tread depth of the replacement tire to the tread depth of the partially worn tires that will remain on the vehicle via the removal of tread rubber from the new tire using a specialized machine that operates as a tire lathe may seem counterintuitive, the value of the mileage sacrificed is considerably less than the cost of rebuilding worn drive line components.
Tire shaving will range from $25 to $35 per tire and is significantly less than the cost of unnecessarily replacing the remaining two or three good tires that still have lots of mileage remaining. But if the tread depth on the remaining tires is 5/32nds or less, shaving may not be the best choice.
Some manufacturers have set parameters for matching the tires used on their four-wheel drive and all-wheel drive vehicles.
- Audi: As stated in their owner's manual, "rolling radius of all 4 tires must remain the same" or within 4/32-inch of each other in remaining depth
- Porsche Cayenne: Within 30% of the other tire on the same axle
- Subaru: Within 1/4-inch of tire circumference or about 2/32-inch of each other