speedo reading high

[john]

so just bought another mk1 berlingo, on the way home i noticed the speedo was reading high, anyone know what could cause this?

[spider]

What reg (assuming not one in your signature) is it plexed ?

Assuming its going to be electronic speedo though regardless.

Standard(ish) wheels / tyres fitted ? Tyre sizes can throw it out a bit.

How high / far out is it (roughly) do you think ?

[Old-Guy]

How much too high. The construction and use regs say (for a Mk1 Bingo) speedo MUST read between +10%, -0%. To cater for tyre wear, rolling radius varying between brands and indeed tyre/wheel options, not to mention age affects and manufacturing tolerances, Citroen will have designed the speedo to over-read by about 6%. Against Sat Navs under good reception conditions, the green Xantia over read by about 5% on newish tyres. Not had a chance to check our latest acquisition yet.

[spider]

I'd forgotten to mention the 10% variance, although I did not know it was only +10% I'd always thought it was +/- 10% for our (EU) vehicles.

[john]

sorry its a mk1 1.4

if im doing 30, it says 37-38, if im doing 53 it says about 60, i only got the car today so i haven't checked the tyre size.

[Mandrake]

John if it says 60 when you're doing 53 (as measured by a sat nav) that's perfectly normal, my Xantia is out by the same amount and has the correct factory tyre size. My previous Xantia was out by exactly the same amount too.

As Old Guy says the regulations say +10% / -0% eg they are not allowed to read slower than actual speed so all manufacturers err on the side of reading too high, by up to 10%.

It's always been like this but it's only thanks to modern sat nav's and digital road side speed signs that anyone is any the wiser!

[citroenxm]

I would be perfectly happy for a "Fast Reading" speedo, then when you are dooing the indicated speed you KNOW your not gonna get done for speeding!

All the S2 Xantias Ive checked have all shown an indicated 5mph fast on the speedo, which is perfect!

[john]

ok both front tyres are 175 65 14

[john]

any help to my other "problem"

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