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| bono | 
				
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							i was going down the freeway today and my girlfriend was following me in her car and said i was doing 110KM/H all the way when i was sticking to the speed limit 100KM/H
 
				Has anyone had problems with there speedo being out after lowering and putting 17's on? 
 _________________ 6 IN A ROW, THE WAY TO GO
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| Ryan0001 | 
				
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							is the rolling diammeter of the tire the same as normal?
 
				if its not, theres ya problem  | 
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| madmax | 
				
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							When you change wheels you need to insure you maintain the same rolling diameter, 
 
				Have a look at this site {DESCRIPTION} Put in your old standard wheel size, and your new wheel size. It will calculate the speedo error and tell you if you have the worng size tyres 
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| data_mine | 
				
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					 {USERNAME} wrote: i was going down the freeway today and my girlfriend was following me in her car and said i was doing 110KM/H all the way when i was sticking to the speed limit 100KM/H 
Has anyone had problems with there speedo being out after lowering and putting 17's on? Could be her speedo is +5% and yours is -5% ??? both within ADRs. Point being, you can't rely on your or someone elses speedo. If you've got a GPS, use that. Using my GPS I've calibrated my speedo to be accurate. It was 3KM/H slow. 
 _________________ 1998 DL LTD in Sparkling Burgundy, daily, 302W, stereo, slow  | 
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| twase | 
				
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							Another way to tell is if you are near a 110kph zone that has the speedo check signs, do 120 to make the maths simple and each K should take 30 seconds, at the 4 K mark you should have taken 2 minutes, if not then simple maths will show the actual speed you did. Don't think this works in VIC any more as you don't get the 10% leaway from the police anymore without getting a fine.
 
				Cheers TW. 
 _________________ BF Fairmont Ghia Series II update.  | 
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| data_mine | 
				
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							@100 1KM will take 36secs, so you won't break the law. (still pretty easy maths)
 
				@110 1KM will take 32.7272727272 @120 1KM will take 30secs @bono - you have your avatar in a bigger format? 
 _________________ 1998 DL LTD in Sparkling Burgundy, daily, 302W, stereo, slow  | 
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| bono | 
				
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							cheers guys
 
				ill check the diamerter when i get home 
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| bono | 
				
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							cheers guys
 
				ill check the diamerter when i get home if it is out can i adjust it myslef? 
 _________________ 6 IN A ROW, THE WAY TO GO
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| uglybob | 
				
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							according to that site, i've gone from 205/65/15 to 235/45/17 - 0.6% of a difference   
				so thats more than good enough for me - if anything, its my speedo that'd be out. 
 _________________ R.I.P. Scotty  | 
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| hornet | 
				
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							I think you'll find the speedos are out from the factory, the speedos usually read faster than you are really going though. 
 
				For instance my speed limiter (ment to be 180km/h) comes on at 173 according to my dyno print out. 
 _________________ 5 Speed EL Futura
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| ItchiOne | 
				
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							Put your cluster into diagnostics mode 3 which shows RPM & KPH.
 
				If the LCD shows you are travelling at 100KPH but the dial shows something differant, then there is a problem with your speedo dial gauge. If they both agree, and its not tyres, could be that you have a non standard diff. Some brighter guy than me would know what diff ratios exist and if this would cause a 10KPH error @ 100KPH actual speed. In my case, my speedo error is 3KPH lower @ 100KPH as shown by the LCD. On my last drive up the Hume highway from Melbourne, my LCD speed matched that of the overhead radar speed check, so i know it is accurate as i wasn't in a datsun Cheers.  | 
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| Punnisher_42 | 
				
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					 {USERNAME} wrote: If they both agree, and its not tyres, could be that you have a non standard diff. Some brighter guy than me would know what diff ratios exist and if this would cause a 10KPH error @ 100KPH actual speed. 
Cheers. mine is like that - with the help of the speed check signs, i found my speedo is nearly 10km/hr too slow at 100 km/hr indicated. I suspect some bright spark changed diff ratios but hasn't adjusted the speedo. Doesn't bother me too much though, i just go a little slower, and know i've got plenty of leeway if the cops come past... will fix if/when i get a new diff. 
 _________________ Regards,  | 
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