The root of the confusion behind the Focus ST's braking system is the split in rotor size that came about mid-2014. When Ford decided to increase the size of the ST's front rotors from approximately 12.6" to 13.2", they did it in the middle of a model year, causing a split in the 2014 model year as to which size rotors are equipped.
The change in rotor size was implemented starting 3/31/2014, meaning if your ST was built after that date, your front rotors are 13.2-inches in diameter. Any STs built before 3/31/14 come with 12.6" rotors. The easiest way to check your ST's build date is to go here and enter your car's VIN.Be sure to carefully read the product pages to make sure you aren't buying the wrong size rotors. And remember, this only applies to the front rotors, which can be found individually and as components in kits. The rear rotors have maintained the same 10.7" diameters since the ST was introduced in 2013. That's why you'll see our rear brake kits and rear rotors labeled "2013-2017," while the front kits will either be "2013-2014" or "2014.5-2017."
Now that you're informed about the split in rotor size, head on over to our complete selection of ST Brake Upgrades!