Should our Boxster have better braking performance?

[Dave R in El Cerrito]

Braking distance depends mostly on tire traction in a straight line, except for the inital period including reaction time of the driver and braking system. The Turanza tires used by BMW are very grippy (my BMW Turanza'a had a 140 tread wear rating, while my Boxster's Conti's have a 280 wear rating). To actually compare braking of the CAR rather than the tires, one should use the same compound on each car.

All tires are compromises between many factors, including straight line and lateral traction and transient response, wet and dry, etc.