I ended up having the dealer update my ABS to the current tire size. Needed to give them the number of tire revolutions per mile. Think we went with 628 with my 285/75 tires (need to double check that) and now the speedo is right on with or without smarty software. Was worth it.Put me in the smoking section but I will take a stock sw with tire adjustment as an appetizer... ... .....![]()