THe LS/GS/RS had 14's, GSR & Type R had 15's. I've had stock 14's and aftermarket 15's and 17's on my Tegs. 17's and 18's look good, but are typically heavy, more expensive and look a little silly with stock brakes and stock ride height (lifted look). I currently have lightweight 15's with a 205mm wide tire. Its a pretty good size for the Teg. It's quicker then than with 17's due to the reduction in diameter of the wheel and the tire, as well as the weight reduction. The stock GSR "blade" wheel was around 14lbs for the 15" so I ended up getting the Konig Feather instead. It's very light 11.5-12lbs and is even lighter than some of the forged wheels like the Motegi Traklite, Volk, SSR, Kosei, and Gram Lights. Check out TireRack and Discount Tire for specs on wheels. It really depends on what you're wanting with the wheels. Looks, performance, price, strength or all of them combined. More important than size and weight is offset. This is often overlooked and can be very bad for the handling and the performance of the car if not taken into consideration when looking for wheels. Hope this all helps a little.