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admlmm · 10-22-2007, 03:37 AM

I can't answer your question about the difference between speedo and odometer but I can share my experience. I have fairly good Garmin GPS and it reads 90kph at 97kph on the speedo, and 110kph at 118kph on the speedo. This means the speedo on my 2002 S manual reads 7 to 8% too high. This is crazy given I have 265/40's on the rear instead of what the manual states should be 265/35's. This means I have bigger tyres that matematically should mean the speedo under-indicate by about 4% yet it seems to over-indicate by 7 to 8%. Must be how Porsche set good fuel economy figures and longevity data.

10-22-2007, 03:37 AM	#10
admlmm Registered User Join Date: Jan 2007 Location: Australia Posts: 4	admlmm I can't answer your question about the difference between speedo and odometer but I can share my experience. I have fairly good Garmin GPS and it reads 90kph at 97kph on the speedo, and 110kph at 118kph on the speedo. This means the speedo on my 2002 S manual reads 7 to 8% too high. This is crazy given I have 265/40's on the rear instead of what the manual states should be 265/35's. This means I have bigger tyres that matematically should mean the speedo under-indicate by about 4% yet it seems to over-indicate by 7 to 8%. Must be how Porsche set good fuel economy figures and longevity data.