Sorry to bump an old thread, but I recently replaced my factory wheels and tires with 16" wheels and 205/50R16 rubber. I've changed the rolling diameter in FORScan to the 1875mm setting. My speedometer is about 2.6% slow which I know seems minor but it's driving me nuts. Has anyone had any luck directly editing the HEX value that that setting appears to change? In the ASBUILT data it changes line 720-27-11 when the rolling diameter is adjusted. Set to the 1875mm setting it reads 0000 A30A 000C. The HEX value of A30A doesn't really correspond to anything.