[T5R92011]

If you have any kind of vibration when braking, you almost certainly need new discs.

A car that is riding on brand new discs and pads all round rolls very smoothly. You can just feel it.

If there is a significant lipped edge on the disc then I have found that you get some low frequency groaning from the pads as the edge rubs against the lip when moving and steering at low speed.

also If you're the sort of people who sits with your foot on the brake at traffic lights, you should change your discs every time you change the pads!