The coefficient of friction between pad & rotor is an indication of the amount of friction between the two surfaces. The higher the coefficient, the greater the friction. Typical passenger car pad coefficients are in the neighborhood of 0.3 to 0.4. Racing pads are in the 0.5 to 0.6 range. "Hard" pads have a lower coefficient but wear less; "soft" pads have a higher coefficient but can wear quickly. With most pads, the coefficient is temperature sensitive - which is why sometimes racers need to "warm up" the brakes before they work well, and also why most brakes will "fade" when they overheat - the coefficient of friction is reduced as the temperature rises. For more information in coefficient of friction, see section of pads.