Unlike brake pads, brake rotors are sold singly, so you can replace or resurface just one brake rotor at a time. While you should always replace your brake pads in pairs, you can replace your rotors one at a time as they wear out.
Are rotors replaced in pairs?
Rotors should be replaced in pairs, and should be the same type (composite or cast) as the original. New rotors are ready-to-install out of the box and should require no additional resurfacing (doing so only shortens their life and risks creating runout and vibration problems).
Can you buy one brake rotor?
You can probably get away with replacing one, but you replace them in pairs so that you can have brake balance between the two wheels. This is the same reason why you would replace brake pads in pairs.
Do I have to replace both rotors if one is bad?
Rotors should be replaced in pairs, and should be the same type (composite or cast) as the original. New rotors are ready-to-install out of the box and should require no additional resurfacing (doing so only shortens their life and risks creating runout and vibration problems).
Are rotors sold in pairs or single?
A: Brake rotors can be bought in pairs, depending on the seller. But for safety sake always, ALWAYS install them in PAIRS!