Some tire stores charge a small fee to rebuild the tire pressure sensor when they replace a tire. It may sound like a scam, but it’s completely legitimate. No shop wants to risk damaging four $100 tire pressure sensors while changing your tires. So the technician unscrews each one from the wheel and lets it drop inside the wheel before dismounting the old tire. Once the sensor’s gasket is disturbed, it can’t be reused. To guarantee a leak-free seal on the reinstall, the shop uses a new gasket, washer and retaining nut. Then a special torque wrench is used to tighten the nut. So you’re paying for the parts and labor.
The tread on a directional tire is designed to provide maximum traction and hydroplane resistance when rotated in a certain direction. Some directional tires have a V-shaped tread pattern, but not all. A directional tire will have an arrow embossed in the sidewall showing the direction of rotation. You can rotate a directional tire front to back and vice versa, but you cannot swap them from side to side.