Thread: speedo accuracy
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Old 7th September 2015, 19:43   #26
another_clean_sheet
Posted a thing or two
 
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Quote:
Originally Posted by arnosvale65 View Post
I have a Scan gauge permanently connected to my OBD2 port and it, like everyone's sat nav, shows an error of 3mph at 30 and 5mph at 60. While talking about this subject does the law still allow 10% error for speeding or has this come to be a generally understood phenomena due to all our speedos over reading?
In my trucking days I always kept my truck on the limiter(55mph) and never once got pulled up for speeding in roadworks. Due to what I have read on this thread about speedos being set to read higher than actual speed in a truck this is downright bad practice. With a digital tachograph any speed over the limit(85kph) comes up as an overspeed and UK police have been known to issue fines and points on this evidence. This speed is actually below the speed limit for trucks on motorways which is set at 60mph. How can that make sense? I know it is an EU rule (85kph) but the Spaniards have an exemption. Why don't we?
The police do not have to allow a 10% error for speeding. This is because if you drive at an indicated 30mph you would not be speeding as your speed would be about 27 mph. To be caught speeding you must have been driving with an indicated speed above the speed limit.
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