Threw the 17s back on and weighed them using 2 different bathroom scales by themselves and by holding them then putting them down. . The 17s were about 50 pounds and the 18s were about 58 pounds. The 17s were around 15% lighter and noticeably taller. I like ground clearance so running the smaller diameter GT stock tires is not for me. I'll either keep the 18s and get 235/55/18s or find 225s or 235s for the 17s. A drop in ride height is something I don't want.