Clio speedo accuracy?

[Pep]

Had my cousins sat nav over the weekend, and my speedo seems to be stupidly out, I know sat navs may read slightly under due to time delay, but my speedo is telling me 55mph and sat nav saying 50mph, and this gets much worse over the speedo....

Are they all this bad?

I have 195/50/15's on the car, so as close to standard tyre size as possible, hardly a difference at all to the standard 185/55/15's.

Ideas?

 

[DrR]

I'd say my 172 one is pretty good, was only out by 3mph at 130+
70 it's bang on same as sat nav. Sat nav should be 100% accurate if going at constant speed.

 

[Beef-Mc]

I've found my speedo reads out at 40 and increases as I accelerate. I'm using the same tyres as yours as well.

Not sure if that's just because my car is set up to run 14's instead of 15's.

 

[j6 pkp]

aren't speedo's set to over read anyway? mines out too, and was out in my clio too!!

 

[Pep]

Beef - all depends on whether the radius is the same as the standard tyre size.

I checked doing constant speeds for a few miles, so definately way out.

Edit, j6 they will be, but 5mph at 50, then going a lot more above that speed seems a lot?

 

[edde]

It will over read by about 10% all through the speed range just the way it is.

 

[AlexS]

Mine over read on 50 profile tyres....

 

[pinky]

Mine says 29 when the speedo says 30mph.

 

[Pep]

Mine over read on 50 profile tyres....

According to this site:

http://www.miata.net/garage/tirecalc.html

the difference between 185/55/15 and 195/50/15 is 1.5% too fast, so when the speedo reads 60pmh it is actually doing 59.1mph, so not much difference, although I suppose it will add up later on in the speed range.

 

[dick]

my speedo reads 1 over up to 95, not gone any faster since ive had sat nav.

tho i think thats due to my taking my dials off and getting them in the wrong place!

 

[AlexS]

Mine over read on 50 profile tyres....

According to this site:

http://www.miata.net/garage/tirecalc.html

the difference between 185/55/15 and 195/50/15 is 1.5% too fast, so when the speedo reads 60pmh it is actually doing 59.1mph, so not much difference, although I suppose it will add up later on in the speed range.

The Lupo over reads too and thats 100% factory even down to the tyre sizes, I think 138 was only 132 jelly babies gps lol.

 

[Brett]

at an indicated 95 on a private road my gps read 91 so there not miles out.

 

[Pep]

Also to note it is a brand new tomtom top of the range thing, with all updates etc, if it makes any difference?!

 

[Pep]

at an indicated 95 on a private road my gps read 91 so there not miles out.

I think it's just mine to be completely honest, is there an adjustment on the cable etc for it, can I get it recalibrated with a lower tolerance?

 

[edde]

at an indicated 95 on a private road my gps read 91 so there not miles out.

I think it's just mine to be completely honest, is there an adjustment on the cable etc for it, can I get it recalibrated with a lower tolerance?

No adjustment is possible unless you fiddle the dials potion but that knock the speedo down by a set amount why does it matter though?

 

[Marky_]

I like to think of mine as 'optimistic'.

 

[Pep]

I think it's just mine to be completely honest, is there an adjustment on the cable etc for it, can I get it recalibrated with a lower tolerance?

No adjustment is possible unless you fiddle the dials potion but that knock the speedo down by a set amount why does it matter though?

Just wondered in all honesty, got 3 points so don;t fancy anymore so I always stick to the speed limit, but at the same time I don;t want to be pissing other drivers off stuck at 55 in a 60 if my speedo is out by a mile.

I could buy a road angel etc but to be hoenst I'd rather not as it would make me more confident of speeding and not getting caught, which I don;t want!

 

[xcore]

my speedo reads 5mph more then actlual speed

 

[GordonD]

Its irrelevant how far out other peoples' speedos are.

Its a matter of how far out yours is.

If you are going at a constant speed, that's important, believe the GPS. It will give you a reading within one whatever per hour. If you are accelerating your GPS will read lower than your real speed, and if you are decelerating it will read higher, because it doesn't tell you how fast you're going now, it tells you your average speed in the previous second.

Clio Sport speedos range from quite close to reading 10% high at least at some speeds. Yours could be anywhere in that range, plus whatever additional error is introduced by your running a different tyre size to standard.