I have 18" x 9" TSW Interlagos that are Rotoforged. They weigh just over 18 lbs. I ran Nitto 05 Drag Radials on the front at the strip... They weigh almost 30 lbs, and as a Daily Driver, I have Michelin Pilot Super Sports, which as a package weigh aroun 43 lbs a wheel, which is 20 lbs a wheel less than the stock 20's... Really helps mileage ( better than stock, even though the tires are 8% smaller diameter), helps performance, and the Michelin's are the best handling tire I have ever used on any vehicle...
'2014 Corvette comes stock with them!
Wheels were around $250. ea at Discount Tire, with their incentives.
Tires came from TireRack, but Discount has them and with free install, would likely be cheaper. The Michelin's are 235-50-18" (27.3" tall) and are about $235. each including shipping. Love-em!