Now I have those bigger tires on when I was coming home last night it sure had made a big difference on the speedo. I run a GPS that has KPH so I mainly use that but the speedo was a lot lower that 30mph when I was doing 50km (30mph). The real test will be going up North to the car show up there. I was getting 13 mpg a so I figure it should be at least 17 now hopefully more