8-10 pounds in the grand scheme of things is not that big of a deal, but shaving weight off your wheel does wonders for tranny life, wheel bearing life, and acceleration. There're different physics in play for both accelerating your car, and accelerating your tires. The lighter your tires/rims, the less your engine needs to work to get them moving. Then you need to worry about your engine moving your car out of it's own way.