Rim weights. Important?
 

How much do the stock 17" rims for the 3 weigh, and how important is it to find rims that are lighter than stock?

Is finding ones that are say 2.5 lbs lighter per corner that important?

I do not know the stock 17" weights off the top of my head....I do know that my 17" MP3 rims were 24lbs a piece not including the tires. 2.5lbs per corner is a HUGE difference. Think of it like this. 2.5lbs per wheel for 4 wheels = 10lbs total rotating mass removed. This is (in essence) the same as going from an 18lb flywheel to an 8lb flywheel.

The less weight your engine/tranny has to turn the more power gets put to the wheels.

And, less wheel wieght means less unsprung weight. Unsprung wieght makes a big difference in how a car handles. You want to minimize the percentage of mass that is not suspended. There are many great lightweight wheels to choose from. Just pick up a copy of Grass Roots Motorsports or any other serious racing rag to find out more.

Thanks guys. I had heard that it made a difference, but didn't exactly know why.

You also need to remember that when you upgrade to a higher size rim that the weight of the tire will go down while the weight of rim usually goes up.

In terms of maximizing your acceleration, wheel diameter is more important than wheel weight due to inertia effects. The farther the weight is from the center of the wheel, the greater the inertia that must be overcome to accelerate the wheel. That's why a lighter, larger diameter wheel can impede your acceleration compared with a heavier, smaller diameter wheel. For maximum acceleration, go with the lightest, smallest diameter wheel you can get away with.

it all depends on what you want to do. if max acceleration is your concern, then go with a lightweight 15" wheel. if you want max handling, go with a lightweight 17" wheel. even though a lightweight 15" wheel might save you 20+ pounds of unsprung weight, the handling won't be there because of the sidewall flex that will occur at high speed. but if you go with a lightweight 17" wheel, your acceleration will suck, but your lap times would be better.