MattyB
Member
Registered: 13th Nov 01
Location: 118.5bhp :D
User status: Offline
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Ok, to cut a long story short about people moaning how their speedos are out and doin crappy little calculations to show speed innaccuracies after a allow wheel size change, this is my results:
Car = 1.2 8v on 16"s with 195/45 tyres
Speedo = 50mph Actual = 48.5mph
Speedo = 60mph Actual = 57.3mph
Speedo = 70mph Actual = 67.2mph
Speedo = 80mph Actual = 76.9mph
Was done using some GPS gizmo which is really expensive and very accurate. Held the above speeds on a flat surface for bout 30 secs each to let GPS calibrate. Just to show, that there aint much of a difference. In fact, i doubt there would be any difference between my car on 16"s and when it was on 13"s, as vaux speedos are notorious for bein bout 5% to high anyway!
Matt
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Makarus
Member
Registered: 25th Jun 02
Location: Nottingham/Derbyshire Boarder.
User status: Offline
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So going on those calculations my 15" on 195/45 should be just about exactly the same as my standard.
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MattyB
Member
Registered: 13th Nov 01
Location: 118.5bhp :D
User status: Offline
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yeah mate - shud b identical - even more so for those ppl who have electronic dash (post 97 cars).....
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SportBoy
Member
Registered: 5th Oct 01
Location: Retford, Nottinghamshire
User status: Offline
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195 45 15 will exajurate (mind the spelling )the speedo reading
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Makarus
Member
Registered: 25th Jun 02
Location: Nottingham/Derbyshire Boarder.
User status: Offline
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No it shouldnt do, the difference is about 1-3mm in the total circumfrence of the wheel, when I had my standard ones I put my new ones on top and the only difference really was the tread on the alloys was higher because they were new.
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SportBoy
Member
Registered: 5th Oct 01
Location: Retford, Nottinghamshire
User status: Offline
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195 45 are a smaller circumfrence than a standard wheel 195 50 r slightly bigger than standard but closer than 45s
[Edited on 25-02-2003 by SportyBoy]
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