[Perfectlap]

more rubber is better. However some 18"s are lighter than 17's which is where weight savings counts. Top shelf rubber is by far the best mod for the Boxster.

I have 18" factory Carreras at ~20lbs each. I don't want to go bigger if the weight is any higher.
~30lb wheels ruin the ride, make the car prone to rattles, wheels bend since you're on less rubber, and it screws with the wheel bearings. 18" is the limit for me, unfortunately there aren't a whole lot of options in Pcar fitment.

Also, the cost of the mere extra inch of rubber opens the door for the tire companies to bend you over the barrell. Tire companies seem to know that a 19" summer performance tire isn't going on a car driven by a guy that doesn't have two nickels to rub together. Sorta reminds of the disappearance of soda machines that actually have 12oz cans instead of those 20 oz plastic bottles. Another 2 cents of sugar water turns into a 150% price increase.