Brake

Currently my main vehicle is a company car, so it is easy to keep up maintenance because I don't have to pay for servicing, new tyres etc.. However there were always two areas that I would not skimp on even when I was paying for my own maintenance, these were tyres (tires for our American cousins) and brakes. If there was any suggestion of wear on tyres or brakes, I would have them serviced without second thought.
As I plan to acquire a second family vehicle soon, I will be ensuring that tyres and brakes are in pristine condition before even turning the ignition key.