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C900 Performance, Mods & Tuning Covers Tuning & Performance modifications for the Classic 900 (C900)

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  #1  
Old 22nd March 2002
90t16Saero 90t16Saero is offline
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I know that there is a way to work this out cos have known people to configure traction control settings with the use of some very clever algebra! Well, that was never me at school so I need an answer to this question please :

Q. I have 17" wheels, so what difference does that make to the reading my speedo gives me? Am I actually going faster than what it says or slower?

Answers on a post card, or maybe in here!
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  #2  
Old 22nd March 2002
Smackrazor Smackrazor is offline
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You will be going slower than speedometer reads...
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  #3  
Old 22nd March 2002
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Alex Alex is offline
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Not exactly a postcard but...

If you are using a 205/45/17 or a 215/40/17 tyre then the rolling radius is exactly the same as the original 195/60/15 tyres. So no change.

If you're using 205/40/17 (a more common tyre) then the total wheel diameter is slightly smaller and the speedo will over read.
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  #4  
Old 22nd March 2002
93Saab900s 93Saab900s is offline
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arent u going faster?
im not using algebra, just logic. ur tires are bigger so they will cover longer with every revolution, so u will be going further than with smaller tires. therefore u will be going faster.
Im pretty sure im right, check the logic out, see if it works in ur head too
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  #5  
Old 22nd March 2002
93Saab900s 93Saab900s is offline
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but it matters on the size of the tires as well
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  #6  
Old 22nd March 2002
Andrew Williams Andrew Williams is offline
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90t16Saero,
try http://secret-secret.com/turbo/DIY/t...turbotire.html
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  #7  
Old 23rd March 2002
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A larger wheel/tyre goes round slower for a given road speed compared to a small tyre. The speedometer reads the rate the wheel is going round.
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  #8  
Old 23rd March 2002
90t16Saero 90t16Saero is offline
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Nice one guys, according to the calc my speedo will be reading approx. 3% too fast! Damn, now i have to go even faster just in case!
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  #9  
Old 23rd March 2002
93Saab900s 93Saab900s is offline
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who was the first one to call it?
me
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