Because summer seems like a reasonable time to start looking for winter tires, I just want to make sure I am not in the wrong here. I am looking to pick up a spare set of wheels for winter tires and prefer to spend the money and buy OEM parts. I found a good deal on a clean set of 2015 Mustang GT rims, no tires that are 5x114.3 with 40mm offset. They are 18 inch rims, so I am looking at going with 225/60R18 tires to get as close to stock size for my 245/45R20 wheels so I don't have that big a difference in my speedometer calibration. Can anyone who has downsized rims give me some insight on this? I know the offset is a little off (38mm on SHO) but I think this is the same bolt pattern from what I can find. I appreciate the help ladies and gentlemen. PS I have a 2011 Non-PP SHO which probably would make a difference, as it did not come with the larger brakes. But the SE FWD cars came with 17 inch wheels, so I assume barrel size shouldn't be a problem with 18 inch wheels.