18 or 19 inch tires?

Kirkster

Light is a relative term.

the 19 inch oem Rays for the 370 Z are
Front Wheels (Sport Package): 23.2lbs(10.52kg)
Rear Wheels (Sport Package): 23.8lbs (10.8kg)

the 18 inch oem Rays for the track package 350 Z
Front Wheels 18.19lbs
Rear Wheels 18.62lbs

Yes the new 19s are wider by and inch in the front and inch and a half in the rear but they are still heavier that the equivalent 18s. Tires are also Heavier. But if I want wider wheels in 18s just as light they are obtainable for less than the price of a set of Volks. (CCW makes them for the z for 2K a set)

But performance between the two is often very subjective, and unsprung weight is a factor in high performance applications.

A shorter/stiffer sidewall on a street tire, while improving turn in response marginally, it just means that you are more likely to dent that expensive rim when you hit pot hole that the truck in front of you was hiding.

Stickier tires are also available in 18s...

The 19s are demanded today because of looks not performance.

Oh, I will be getting the Sports Package when I buy my Z in a month or two, I am buying it not for the Wheels, but for the brakes... Ice mode was notorious on the 350 base and touring package without the Brembo brakes.

Flame suit on...