Went to a shorter tire and cannot adjust tire size. It saves it in there but nothing changes when I drive it. It seems to be stuck on the tire size that I had in with my old Smarty. No matter the number I put in, it reads 2.5 mph faster than I'm going according to my GPS, it was dead on with the GPS with the old tires. Anyway around this or am I going to have to find someone with a Smarty to adjust it, kind of a pain in the ass if so?