Bud, the size of tyre will not affect the speedometer, only the actual physical speed. The Speedometer gets its readings from the gearbox sensor, of which is a gear reading how many times its spins multiplied by the selected driving gear, thats whats outputted to the end of the axles and to the wheels.. what the wheels do with it then is out of the control of the speedometer.
here you go .. a good second opinion
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