Speedo calibration

    My SS was a just an SS....the dealer upgraded it to an SL with the bigger tires, wheels and infotainment center....
    Changing to those bigger tires...did it change my speed reading and do you think the dealer would have made any needed changes to make it read correctly? If it's off how will I know and how much would/could it be off?

    I believe the dealer should have reprogrammed your ECU to handle the larger tires. A neat way to check your speedo performance if you have an Android phone is the Speedometer app (don't know if Apple offers a similar app, I'd assume so).
    According to the Discount Tire Tire Size Calculator (Discount Tire) the SL front tires are 3.5% larger than the Base front tires and the SL rear is 2.8% larger than the Base rear tire. This means at the same rpm, the SL tire should be turning at around 67 mph at an indicated 65.

    Edited once, last by BKL ().