In which case, your vehicle does not meet the legal requirements. The speedometer must read the actual road speed to within -0%, +10%. In other words, it is allowed to overread by up to 10% but must not underread.s4woody wrote:... but were relying on a speedometer thats mass produced whilst driving with the wrong tyre pressures or even worn down tyres...
But, even so, how you determine your speed is up to you - exceeding the limit is still an absolute offence. I always drive to the speed displayed by my RoadPilot.