Depends on how worn they are. I wouldn't suggest running on them for long. Can cause quite a few things to go bad including wearing out the pads if they aren't all ready worn out. Would get new ones as soon as possible.
If the rotors are worn too thin, they could snap apart while braking, leaving you with no braking power at all.
They can be a bit worn, but not much. Look at a new one or ask at parts store, thickness, then measure yours.
if your rotors r worn you see little groves on them that go all the way around these grove tend to have a rust color
Usually this is caused by worn out brake pads. There are 'squealers' on them that begin to make contact with your rotors after the pads are almost worn out, causing them to make a very unpleasant noise. Continue to drive the vehicle for very long after it squeaks and you'll begin to do expensive damage to your rotors. You can replace them yourself for about $60 in parts if you know what you're doing in about 20 minutes, or take it to a shop and be charged a few hundred dollars.
more than likely you need rotors or the caliber slides are worn
damaged/ worn brake rotors.
When rotors need to be changed usually the pads have worn down. It is always a good idea to change pads when changing rotors.
depends on the condition od the pads. If worn or have groves etc from the rotors then replace.
Pads are worn down Rotors are rusty and scoured Dirt and grit have been trapped between pads and rotors
If you hear the squealing when applying the brakes, the pads are worn out and need replacing ASAP. Failure to replace the pads immediately will result in worn out rotors which will also need replacing. If the squealing noise is not when braking it may be a worn drive belt.
More then likely your front brakes are worn, take it in to get it serviced. Needs new brake pads and rotors turned.
The brakes may be hot after a long drive, and the water will cause rapid cooling, possibly warping the brake drums or rotors.