Each bus, truck, and truck-tractor must be equipped with a speedometer indicating vehicle speed in miles per hour and/or kilometers per hour. The speedometer must be accurate to within plus or minus 8 km/hr (5 mph) at a speed of 80 km/hr (50 mph).
[70 FR 48054, Aug. 15, 2005]
§393.82 — DOT Regulatory Guidance
Question 1: What does the phrase "reasonable accuracy" mean? Guidance: "Reasonable accuracy" is interpreted to mean accuracy to within plus or minus 5 mph at a speed of 50 mph.