1 lb of removed unsprung weight is roughly equivalent to removing 10 lbs of sprung weight, dropping 6 pounds per wheel/tire assembly is like stripping 240 lbs off your vehicle. The lighter wheels/tires also allow the shocks, springs and sway bars to work more efficently, similar to stiffer shocks, springs and sways installed with the OE wheels/tires. Big/heavy wheels/tires do the opposite, 10 lbs per assembly is like loading 400 lbs of stuff into the vehicle. Ultra low profile tires also beat the crap out of suspension components due to ZERO sidewall flex, not to mention a small road hazard such as a 2x4 will have you replacing a cracked wheel, when an X with 19"s or 20"s will suffer no damage at all. It's a BMW, not a '62 Impala, try to bump up performance with mods, not bling factor.