It's been a while (C5 Adventure)

Tell us your ongoing tales and experiences with your French car here. Post pictures of your car here as well.

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Mandrake
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Re: It's been a while (C5 Adventure)

Post by Mandrake »

Trainman wrote:OK the tyres fitted to the car when I bought it were 195/65R15 the current wheels are 205/50 17
http://www.tyresizecalculator.com/tyre- ... dimensions

For the first tyre, rolling circumference 1994mm and 502 revolutions per km, for the second one 2000mm, with 500 revolutions per km. That's a 0.4% difference which is completely negligible, as up to a few percent is allowable.

Hell Razor5543
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Re: It's been a while (C5 Adventure)

Post by Hell Razor5543 »

But we do not yet know if these are correct for the car itself. I went down (when elma asked) and checked my C5, and the tyres match what the label says. That gives my tyres a circumference of 2019mm.
Last edited by Hell Razor5543 on 21 Mar 2017, 11:38, edited 1 time in total.

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Mandrake
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Re: It's been a while (C5 Adventure)

Post by Mandrake »

Hell Razor5543 wrote:But we do not yet know if these are correct for the car itself. I went down (when elma asked) and checked my C5, and the tyres match what the label says. That gives mt tyres a circumference of 2019mm.
Well, what tyre size does it say on the door card, Steve ?

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DHallworth
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Re: It's been a while (C5 Adventure)

Post by DHallworth »

The tyre size on the V6 I had was 215/55/16 which gives them a rolling circumference of 2019mm, the same as James's. I'd guess that all C5 wheels and tyres would give the same rolling circumference (different sized wheels with different sized tyres give the same total I'd of thought).

Hope that helps!

David.

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Re: It's been a while (C5 Adventure)

Post by elma »

Yes, to do the maths and compare to see if the speedo would be affected the oem tyre size (as on the door label) is needed.

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Re: It's been a while (C5 Adventure)

Post by Trainman »

I'll have a look later, i'm at work now. :(

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Re: It's been a while (C5 Adventure)

Post by Trainman »

sticker says 205/65 R15 94H
IMG_0172.JPG

Hell Razor5543
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Re: It's been a while (C5 Adventure)

Post by Hell Razor5543 »

And do the tyres match?

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myglaren
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Re: It's been a while (C5 Adventure)

Post by myglaren »

Trainman wrote:sticker says 205/65 R15 94H

IMG_0172.JPG
That is the same as mine and my speedo is very accurate.

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Re: It's been a while (C5 Adventure)

Post by elma »

Your speedometer error is unlikely to be down to tyres then. You are -1.7% from OEM and your speedometer should over read by about 1 mph all the way up to 100mph.

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Re: It's been a while (C5 Adventure)

Post by Trainman »

Hmmm....... OK, I wonder then if it could be the Satnav that's out? I'm using one from my phone on the odd occasion I need one (and before you ask it's one called WAZE). I'm sure I've seen something about a speed checker somewhere in the apps.......... looks like something to play with this weekend.

Thanks for everything guys ;)

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Mandrake
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Re: It's been a while (C5 Adventure)

Post by Mandrake »

I can't see any way that the satnav could be out, but you could try another one just to be sure.

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Re: It's been a while (C5 Adventure)

Post by elma »

Steve the best way to check is to hire a laser speed gun, they cost bugger all to hire these days and are as accurate as you'll get.
Satnav isn't as good at working out speed as people think. It's only accurate in a straight line, on an accurate map and if it has good signal, I find all 3 of mine have good days and bad days as far as accuracy is concerned.
The other thing to do is drive along with a friend with a known good speedo at a set speed and speed match them.

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Re: It's been a while (C5 Adventure)

Post by Mandrake »

Satnav is very accurate if you use it properly - drive on a clear road without any tall buildings or trees around with a good view of the sky, drive in a straight line and drive at a constant speed. Give it a few seconds for the reading to settle, then it will be accurate within 1mph easily.

Speeding up or slowing down, cornering, driving between buildings etc will all cause temporary aberrations in the reading. I would trust satnav used properly over comparing it with another car.

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Re: It's been a while (C5 Adventure)

Post by Trainman »

I've just downloaded a speed app to my phone, I'm heading up the M6 shortly so hopefully I can get a reading along there............