I mean it can't be hard. Has anyone figured it out yet? Is there an option within the programming to change tire size to calibrate speedo or is it a bit more complicated than that.

My research says nobody has bothered yet. I know it takes me 4 seconds in my Jeep to change the speedo calibration from 29" tires to 37"'s.

Any tuners enable this? Wanting to pick up a set of oversize tires for, reasons.