VStar650CL wrote: ↑Sun Oct 03, 2021 3:41 pmCalculating the profiles shows about a 9mm difference in rolling diameter, which equates to about a 1.3% reduction in wheel speed. However, the speedo in your Altie is programmed about 1.5% low at the factory, so it will pretty much make your speedo spot-on accurate. So long as all 4 are changed over, I wouldn't foresee any issues with the ABS, VDC, or any other systems.