There's little doubt that a well maintained E53 X5 can provide exceptional braking performance, especially when you consider it's size and weight. BMW achieved this by using a combination of softer composite brake discs together with a pad compound that, although very effective, unfortunately causes the rotors wear down to their minimum effective thickness at a quicker rate than most. To ensure the X5's braking performance is upheld, we recommend replacement with Zimmermann discs. As an original equipment supplier to BMW, Zimmermann's discs are manufactured to the highest standards in Germany and come with their own Z-Coat to prevent the discs from rusting. Priced by the pair.