The most important factor when buying new brake discs is to ensure they are the right size and specification for your car. Depending on the vehicle you own there can be several options in terms of size, and online parts retailers will often provide specific makes, models, year of production and trim level to ensure you select the right part. We would also recommend buying the best quality discs you can afford, as cheap brake discs can be a false economy. You don't necessarily need to buy discs directly from a main dealer, but would recommend OEM quality where possible.