When I take my car into the shop to get tires rotated, is it assumed by the mechanics that the tires need to be switched around a certain way? Or do they check the tread on each tire to determine which position it should be rotated to in order to give me the best life out of my tires (based on the car being front-wheel drive vs rear-wheel drive, etc...)?
It does indeed vary according to the type of car - and also the type of tyre, as some are directional (which means they have to stay on the same side of the car).
According to BlackCircles:
- FWD: Front to Rear, same side. Rear to Front, swap sides.
- RWD: Front to Rear, swap sides. Rear to Front, same side.
- 4WD: Front to Rear, swap sides. Rear to Front, swap sides.
- Directional: Swap Front and Rear but keep the same sides.
Primarily they rotate by a pattern. They are also looking for wear that might indicate an alignment issue or could cause traction problems.
According to TireRack.com;
Tires should be serviced periodically following the rotation patterns provided in the vehicle's owner's manual or as established by the industry.
There are many patterns depending on vehicle and tire types, but basic rotation for most automobiles are like below.
Image credit: TireRack.com;
You should ask the place doing the work how they do it. They should be willing to explain it to you.