My camry has about 50 000 mi,How do I know if I need rotors or just new brake pads?
The need for new rotors is based on a few different things: runout (the amount of warpage of the rotor), scoring (the depth of any gouges in the rotor surface), and thickness (the actual surface-to-surface dimension of the rotor).
If the rotor doesn’t have a lot of runout and the braking surface is smooth, then you are good to go. Thickness really comes in to play if you need to turn the rotor (ie machine it down). If it is too thin to have turned, then you pretty much have to buy a new one.
You did not say what car, but most modern cars are equipped with cheap thin light weight rotors. While you might get two sets of pads out of them, I suggest that you replaced them at each pad change.
When I said cheap, I did not intend to suggest they are poorly made, although some are, rather they are inexpensive. They are cheap enough that the cost of resurfacing them is only a little less than replacing them.
If you reuse them and if they then warp or have other problems before you need new pads (and it is not unusual that they will) then you have lost a lot more than you thought you might have been saving by not replacing them.
Yes, I replace my rotors with each pad replacement.
depending on where you live it costs around 12 dollars per side to “turn” them (resurfacing)
it costs around 35 to 50 bucks for new ones. depending on which model car, some are cheaper than that.
i replace mine every other pad replacement.
if you are having this done at a shop then you are going to have to do what they want so they will warranty the job. nothing more frustrating that a partially done brake job; neither the customer NOR the shop is happy when each other blames the other for why it didn’t come out ok.
i think realisticlly you have gotten your moneys worth out of rotors over the course of 50k. time for new ones.