Safe Speed Forums

I knew that speedos had a tolerence level but i did not know how far out mine was until i bought a road angel. When doing 70mph on my speedo the reading on the road angel is about 62mph. It gets worse the faster you go....allegedly. Which one shows what any cameras or speed guns will read ?

The speed measuring devices used to enforce vehicle speeds are meant to be calibrated and accurate, so they should match up with your GPS. Speedos should be over-reading by between 0 to +10%, hence drivers shouldn’t be able to blame their speedos when caught speeding, but there’ll be a proportion that fall outside this tolerance band. I don’t think a reading of 62 for a 70 is unusual.

However, in the case of Lidar meters (LTI20-20 et al) – anything goes

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Views expressed are personal opinions and are not necessarily shared by the Safe Speed campaign

I noticed something interesting, the speed at which I travelled to and from work had dropped by about 5-10mph. I was really confused, I wasn't doing anything different, it didn't seem like I was driving slower yet the speedo said I was. Eventually I realised that this was because I had changed the tires! The speedo was now pretty much accurate whereas before 70mph real was about 75mph on the speedo. It seemed that at 30 it was about right but the faster I got the more out it was, but now all speeds on the speedo matched the GPS reading.

So I hadn't actually changed, the car had.

However this made me think of something.
Mr. Drive By Numbers drives at exactally 70 according to the speedo (which is at first really 65) and has become used to this. He has done it every day for months. Then he has the tires changed. (or whatever might affect the speedo, but he doesn't know how cars work or even realised it's happened etc.) He would still get the speedo up to 70, but now he is actually doing 70, 5mph faster than he has been used to! He might now be driving faster than he can handle, but he thinks it is ok because it's what he has always done, he thinks.

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Andrew.

What's worse IMO is people overtaking in L3 at 65mph(70mph on speedo) with the "I'm not breaking the law for you chum, you can jolly well wait", attitude.

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Shooting is good for you and too good for some people.

I used to get annoyed there. However, these days I just lay back. These people may well be at or near their level of capability.

In my experience, they do move back over as soon as reasonably practicable, provided they are not hounded.

If the diameter /circumference of the tyre is changed, the amount of road covered in a rotation of the wheel is also changed. This applies even if you fit tyres which have the same size as the previous but are of a different profile.

Reminds me of a friend on his highly-tuned motorbike. Takes it out for some serious post-tune up wellie, gets stopped by the police.
"We've got you doing 135m.p.h., sir".
And he said (really, I swear it) "is that all? the speedo said 150".

LMAO

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Semper in excreta, nur quantitat variat.