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Model specific boards => Golf mk3 => Topic started by: Milby on 31 March 2012, 20:39

Title: speedo
Post by: Milby on 31 March 2012, 20:39
i noticed the other day on a nice drive down south my speedo was reading about 80mph and the sat nav was reading about 70mph is there any way to get the speedo calibrated ??
Title: Re: speedo
Post by: dom on 31 March 2012, 20:44
What size wheels/tyres are you running? Incorrect tyre size can cause the speedo to read wrong
Title: Re: speedo
Post by: thai-wronghorse on 31 March 2012, 20:45
This^^^

Plus the fact your car speedo should read approx 3-5mph above your actual speed which is more likely to be recorded on your sat nav.
Title: Re: speedo
Post by: Milby on 31 March 2012, 20:48
185/55/r14
Title: Re: speedo
Post by: dom on 31 March 2012, 20:55
185/55/r14

When I had my Mk3, it had 205/50/15s on and the speedo was pretty much bang on.

The difference between 205/50/15 & 185/55/14 is -4.45%

That amount accounts for just over 3mph when doing 70, combined with the speedo over-read you get as standard is about right. If you want to get it to read more accurately then you need larger tyres.
Title: Re: speedo
Post by: mrsaunders on 01 April 2012, 00:04
i'd say its probly the sat nav, lets face it there not that accurate are they
Title: Re: speedo
Post by: Dogbot on 01 April 2012, 00:08
As said above its the tyres throwing out the speedo, the sat nav  speed is done on gps, although as much as a second time delay it's the most accurate of the two
Title: Re: speedo
Post by: mrsaunders on 01 April 2012, 00:14
yeah they are ment to be dead on but its probly just the one i used  :laugh: i have had experience with a dodgy one
Title: Re: speedo
Post by: Gavv8 on 01 April 2012, 09:05
The police use evidence based on speedo speed not gps ..nuff said..
Title: Re: speedo
Post by: thai-wronghorse on 01 April 2012, 09:11
And coincidentally their sophisticated  radar equipment isn't based around 15 year old analogue VAG clockwork.