I am new to site and just bought a 2014 GT500 with 187 miles on it 4 days ago. After reading some of the manual and talking to a couple people it was recommended that I put different tires on my car for cooler weather. I am looking for advise on what size rims and tires. I know you have to be careful because of the brake calibers. I called Ford SVT and all they only told me told me 19x9 in rims from a 2010-2012 GT500 and P255/40R-19 tires all around. Tire also must be V rated or higher and 93 load rated or higher. (same thing in manual) But going through the forum I see people putting different sizes on there cars, putting 20's all around, and mixing 19 & 20 in rims like the car came with. I am also concerned with aftermarket rims and sure they will fit. So for you people who have Shelby blood running in your veins can you please help me on this? We all had to start out like this and the only way we learn is by asking. If I could get some recommendations.