I've had my Car for a week now and i'm pretty sure my speedo reading is out. Its a 1.9TDi Ambiente with 14'' wheels ( I believe this can effect readings?) which I presume have always been on the car. When i'm doing 30mph on the clock, it feels more like 25mph. I go through an area of 3 of those 'your speed' panels and they tend to show 26, when my speedo says 30! Is there anything I could do? And if so i'm guessing its expensive if not:(

Any advice would be appreciated.

Mines 10% out (satnav confirmed) which would be 27mph when showing 30. Can be calibrated via VAGCOM/ VCDS, but how I don't know. I am quite happy with it, I know the varitations, and if others drive it, it will overread and should adviod spees traps and so on.

(Think with 14inch wheels it should have a 185 profile tire on it.)

HTH, Joe

(Think with 14inch wheels it should have a 185 profile tire on it.)

IIRC, the Ambiente spec has the 14x5 Steels, so the tyres would be 165/70/R14, the 185/60/R14 refers to the 14x6 Steels

Cheers Triggerfish,

Sounds like it might be the normal then. Very true on the Speed Traps!

Ta!

Do you have a sat nav? they're much more accurate than speedos.. they all tend to over read, which is a good thing! being 5mph out though at 30 is a bit ott, at 70 that'll be much higher.

All speedo's will over read to greater/lesser extent!

I've got a Sat Nav which I used on my old Yaris, on the Motorway it was always about 3-4 mph lower than the speedo, but I was never sure how reliable a Sat Nav is, so I always went by the speedo for 'points' sake.

I have a 1.4 16v Elegance estated on 185/60/R14's on the OEM 14" alloys, anmd mine is 10% over stating the speed as well.

It seems that this is the norm

IIRC, the Ambiente spec has the 14x5 Steels, so the tyres would be 165/70/R14, the 185/60/R14 refers to the 14x6 Steels

Mine is a Comfort, later Ambiente and came with 14inch Skoda alloys (ex-demo I think). The tyres on that are 185/60R14.

But to be fair, I have no idea what anything tyre related means except for the tyre size.

Mine is a Comfort, later Ambiente and came with 14inch Skoda alloys (ex-demo I think). The tyres on that are 185/60R14.

But to be fair, I have no idea what anything tyre related means except for the tyre size.

It's dead easy

185 - that's the width of the tyre in mm

60 - that's the height of the tyre expressed as a percentage of the width, so your tyre sides are 111mm measured from the edge of the rim to the top of the side

14 - that's the dia of the wheel in inches (rather helpfully tyre and whell sizing is a mix of inches and mm)

6j - is the width of the rim in inches. so 6 inches so 152.4mm. So your tyres over hang the rims by 15mm or so on each side.

Lokk onn wikipeadia, there is a good explanation on there

Cool, thanks. That now leaves the confusion of ET, offset and so on. (don't bother explaining those!)

It's never something that really bothered me, I can't change the wheels as the insurance prohibits it. :(

I've noticed the Speedo is way out on my Fabia too.

At an indicated 70, the car shows 63 on the gps.

It's easily 10% out all the way around the speedo.

Another concern to this, is that if the speedo is way way out, how does this effect the true mileage reading?

I need to do a known long distance journey in both my Fabia and my golf (the golf's speedo is almost 100% accurate) to see if the mileages come out any different!

Mine is out by approx 10%.

According to my sat nav at least. Mrs Grrs SDI is exactly the same.

My last car was a VW Bora and that was also the same.

This must be deliberate. The speedo/tachograph in my works lorry was spot on to my sat nav and that's calibrated regularly. So I'm taking my sat navs readings as gospel. My displayed 90mph (on a private road of course... ahem....) is only actually 81mph.

What a swizz. I'd much rather it was engineered to be spot on. Very un-German...

Another concern to this, is that if the speedo is way way out, how does this effect the true mileage reading?

Should be ok. Check the miles covered on a long journey vs. the route on a satnav, should be quite close.

Also, sit at a constant speed (say 60,70mph) reset the average speed function on the trip computer, once it gets its first reading, it should tie in with the real speed/whats shown on a speedo, meaning the odometer and so on get the correct mileage.

Cool, thanks. That now leaves the confusion of ET, offset and so on. (don't bother explaining those!)

ET is offset. The best way to describe offset is, Imagine looking at the bare wheel end on, Now draw an imaginary line vertically through the centre of the wheel. The offset expressed in mm is the distance from the centre line of the wheel to the mounting face of the wheel.

HTH:thumbup:

Thanks good image as well.

So a large negative offset would mean it would hit brakes/arch liners etc, which is where spacers come in, to give clearence?

Ive read somewhere that you can somehow get the true speed reading to come up on the digital display, but cant remember where. Anyone got any ideas

Climatronic equiped cars only, Golf platform cars!

how does that work then??

I too was very sceptical about my true speedo reading; I invested in a Microfuzion GPS Camera detector Micro Fuzion Speed Camera Detector store: The number one GPS based 100% legal speed camera detection system which gives you your actual TRUE Speed on it's Digital Display, about £80.00.

It also gives you the permanant and possible mobile camera alerts, I think it's brilliant. Don't be tempted to buy the Lazer version (which is slightly dearer) because it is classed as illegal whereas the GPS version is LEGAL. Although it comes in a silver colour I gave mine a flashover with a black spray can.

DB.

Edited 14 October, 200916 yr by mogwye

how does that work then??

http://briskoda.net/general-technical-guides/vag-com-octavia-climatronic-display/49981/

Just an Update to confirm my initial feelings.

Just drove back from London in my Fabia. Filled up at the petrol Station, reset trip meter.

My friend did the same in his brand new 2009 Fiat 500 Abarth.

We followed each other all the way bumper to bumper.

Got to my front door,

Fabia reads 83.6 miles

Abarth reads 80.2 miles.

That's a 4% difference between the two cars.

I won't know how accurate the Fiat is, but it does highlight that not only are speedo's out, but so is a car's total odometer!

my vRS is 1mph out at 60mph, its the most accurate car ive ever driven, ive had some which have been 10% out or more

I get the feeling going through cameras that the VRS speedo is less optimistic than most other cars as I seem to have to slow down to mix with the other traffic - the industry standard is about 10% to give a margin for error, etc. Cameras are usually set to operate at about limit + 10% + 2mph - so 35 in a 30 and an amazing 68 in a 60 limit, but don't quote me on it if you end up getting done! I got that off the west mids speed camera website btw

The age of your tyres may give a difference too, imaging a new tread depth of 12mm compared to worn donw of 2mm - its 20mm on the rolling diameter = 63mm on the circumference - not enormous but worth noting?