Porterfield R4 AP683 Brake Pad Rear BMW E46 M3

Designed specifically for heavy duty motorsports, the R-4 brake pad was the first and is Portfield's original Carbon Kevlar brake pad. Being able to maintain an average of .50 friction level within a very wide temperature range gives the R-4 pad astounding versatility and makes it very suitable for a wide array of various track conditions. Another inherent characteristic of Porterfield's Carbon Kevlar material is how quickly the pads warm up to race temperature which is quite helpful during restarts, and when track time is limited. Optimum R-4 operating temperatures are 450°F and above. When used with cast iron and steel alloy rotor, the R-4 compound requires minimal bed-in period.