Why go from 17” wheels to 18”?

[PaulE]

I’ve got a set of 17” Boxster II wheels I bought and the 18” Lt Alloy Carrera wheels the car came with. With OEM Pilot Sport N3 tires mounted the front 17 and 18”s weigh the same. The 18 inch rears weigh less than 2 lbs more than the 17’s. Every lb counts with unsprung weight but gaining an inch diameter in rim is offset by losing a half inch of rubber sidewall on both sides of the tire. For street driving there is no difference but an extra half inch of sidewall to protect your rims from potholes is nice. On the 18’s I just replaced the tires with Pilot Sport 4S tires bought at Costco and mounted by them on my refinished wheels. They do a great job at Costco and with the deal they had on Michelin’s last June, similar to their current Bridgestone deal, I was out the door for less than just buying the tires from Tire Rack. Costco is the only tire place I’ve seen that gives you nitrogen for no charge and religiously uses a torque wrench for the final tightening. YMMV.