Home again

My odometer says I just finished 9,516 miles, but the GPS trip meter says 9,634 miles, and I set them at the same time. Personally, I trust the GPS. Every since I got new tires, the speedometer has read low. If the needle says 60, the GPS reads a point or two higher. It makes sense. New tires have a greater circumference than the old ones. More inches per revolution that the speedometer has no way of knowing about. Actually, I had expected more of a difference. Maybe since the tires are now ten thousand miles older, it's evening out. I suspect it's the older two tires, the ones that I had rotated to the rear that make the difference.