Centerlines, 15 x 8.5 with... I'm pretty sure, 3.5 inches of back spacing. BF Goodrich drag radials, 27560R15. Plenty of clearance at the springs and I HAD plenty of clearance at the quarters until I flipped the front spring mounts to lower the car (SS springs). Now it's REALLY tight. Had my buddy trim and smooth the inside wheel well lip on the driver's side nd it was still scraping on big pumps in the road. I put a pinion snubber in to limit travel (had to cut it down and weld it together). Looks really cool in my opinion, but the ride is pretty harsh.