DanielJ
Member
Registered: 21st Nov 01
Location: gwent, south wales
User status: Offline
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as above cos i think me speedo is 10mph out
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Jamie
Member
Registered: 1st Apr 02
Location: Aberdeen
User status: Offline
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I was dead next to my mate and he was in his brand new standard fiesta.
he was doing 70mph and i was sitting at 68mph so cant be that much out.
Wait and see what the millions say.
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DanielJ
Member
Registered: 21st Nov 01
Location: gwent, south wales
User status: Offline
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ai will do  im gonna get me m8 2 drive along next 2 me on weekend i think
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Meat-Pie-SRI
Member
Registered: 10th Apr 02
Location: Berkhamsted, Drives Mk4 R32
User status: Offline
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there was a web link put on here a while ago that calculated the difference that different size wheels made. do a search for it!
having someone drive next to you is not likely to be very helpful as most speedos are inaccurate!
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DanielJ
Member
Registered: 21st Nov 01
Location: gwent, south wales
User status: Offline
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i no but we both got 17s an both got corsas
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Cursa
Member
Registered: 30th Mar 02
Location: Dumfries & Galloway
User status: Offline
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Depends how much rubber you have on them doesnt it!
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DanielJ
Member
Registered: 21st Nov 01
Location: gwent, south wales
User status: Offline
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wtf? tyre size wudnt matter
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CorsaGSI_DK
Member
Registered: 10th Jun 02
Location: Copenhagen, Denmark
User status: Offline
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Come on guys!!!
It is simple geometric calculations! If you can't calculate the size of your wheel yourself then try this ---> http://www.miata.net/garage/tirecalc.html
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dja
Member
Registered: 16th Nov 02
Location: Bolton,lancs
User status: Offline
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of course tyre size matters!!
different profiles will give a different circumference!
eg a 60 profile tyre will have a greater rolling circuference than a 50 profile tyre.
thus the speedo reading will be out.
Dave
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DanielJ
Member
Registered: 21st Nov 01
Location: gwent, south wales
User status: Offline
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quote:
Originally posted by CorsaGSI_DK
Come on guys!!!
It is simple geometric calculations! If you can't calculate the size of your wheel yourself then try this ---> http://www.miata.net/garage/tirecalc.html
thank u 
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DanielJ
Member
Registered: 21st Nov 01
Location: gwent, south wales
User status: Offline
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still no luck, mine seems 2 b 10 mile an hour slower, its on 50mph an it only feels 40
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CorsaGSI_DK
Member
Registered: 10th Jun 02
Location: Copenhagen, Denmark
User status: Offline
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Well...are you allowed to change the tyre size that much from original??? In Denmark we are NOT allowed to change the wheel size (diameter of whell...alloy and tyres) more than plus/minus 5 percentage from the original wheel size.
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dja
Member
Registered: 16th Nov 02
Location: Bolton,lancs
User status: Offline
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You can put what you want on here in uk,as long as each axle has the same size tyre on,and the front tyres must be the same size as the rear or narrower.
Dave
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Nailz
Member
Registered: 21st Mar 03
User status: Offline
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shunt alter anything it calculates from the axle brace not wheel
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MattyB
Member
Registered: 13th Nov 01
Location: 118.5bhp :D
User status: Offline
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I've tested mine using a GPS system which is as expensive and as accurate as u can get. I posted this up before, but basically:
my 1.2 8v on 16"s with 195/45 tyres
50mph on clock = 48mph
60 mph on clock = 57mph
70mph on clock = 65mph
draw ur own conclusions. Oh and thats with a mechanical speedo cable dash.
Matt
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Frankee_B
Member
Registered: 18th Jun 02
Location: Strood (Kent)
User status: Offline
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How the fuk do u get it sorted out? do u av 2 get it on the dyno? how much is it gona cost? fuk dis, i aint flashed again.
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Jamie
Member
Registered: 1st Apr 02
Location: Aberdeen
User status: Offline
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quote:
Originally posted by DanielJ
still no luck, mine seems 2 b 10 mile an hour slower, its on 50mph an it only feels 40
Mine feels the same, sitting at 70 feels more like going 60. 
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Plymouth_Corsa
Member
Registered: 23rd Sep 02
Location: Plymouth Drives: Carzone Corsa
User status: Offline
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There is another site, that measures the speed the vehicle is travelling at, and the speed it says on the speedo is below that of what the car actually does when over 70mph....my friends 205 gti was doing 90 and i overtook him, and mine read 85!!!
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vauxtillidie
Member
Registered: 27th Dec 02
Location: Manchester Drives: Cav turbo/Corsa C20XE
User status: Offline
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try this site 
http://www.paspeedo.com/calculator.htm
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Jason Iles
Member
Registered: 19th Jun 01
Location: Bristol
User status: Offline
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With the first calculator thing i'm 0.1% out
thats not bad. That means when doing 60MPH on the Speedo I am doing 60MPH
[Edited on 24-03-2003 by J 11ESY]
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miles
Member
Registered: 25th Mar 02
Location: plymouth Drives: Astra Sport
User status: Offline
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With 17s you wont actually be going faster than the speedo reads, well, maybe +1/2% or something.
Speedo's read slow as standard.
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Dinokid
Member
Registered: 25th Dec 02
Location: Winnington, Cheshire Drives: Honda Civic Marlin
User status: Offline
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Speedos are cable driven from the rotation of the wheels so if its a bigger wheel then the wheel will rotate less to go the same speed as a small wheel, so surely a speedo would read low?????
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