For same brand and size. Difference between new and worn tires roughly 1 % in correction.
With kickstand down, measurement from the upper axle to the ground. 13 13/16" new, 13 5/8" worn.
Multiple passes(7 passes) over a measured mile. Steady speed mph and stop watch in hand. Calculated the adverage of the seven passes. Found +4.4% error in speedo on a worn tire.
Over a measured four mile course. The odometer was accurate very hard to see detect any error.