Stock tire size on my '87 was revealed to be reading slow when we borrowed "Samantha" the GPS from neighbors for a trip. In addition to reminding us about all the turns we'd missed she informed us that at an indicated 65 we are really doing about 58. Here I thought everyone else was really hauling and it turns out I'm the one who is not. Stephen --- On Mon, 5/6/13, Mike Miller <mwmiller6@ATT.NET> wrote: From: Mike Miller <mwmiller6@ATT.NET> Subject: Re: speedometer accuracy To: vanagon@GERRY.VANAGON.COM Date: Monday, May 6, 2013, 4:54 PM I'm interested too. I've put 225/75-15 BFGs on and my speedometer is off, according to my GPS, by more than the percentage the difference in size between that and stock predict. I thought the stock VW speedometers were off but on the high side as Karl indicated, but the percentage is greater, meaning the stock was reading too slow? Also I have a scan gauge and it indicates about 100 RPM less than the diesel tach idicates? Which is likely to be more correct and how does each determine RPM? Mike in Cotati
________________________________ From: Karl Ploessl <karl.ploessl@GMAIL.COM> To: vanagon@GERRY.VANAGON.COM Sent: Mon, May 6, 2013 1:29:08 PM Subject: speedometer accuracy so I finally got a GPS in my van. And what do I notice? Speedometer says 60 mph and GPS says 45 mph! At 70 (speedometer) the GPS says 62! I am running Michelin Agilis 61 in size 185/14 C and it is a Westy 81 aircooled. And it is in Delaware to satisfy Scott. The question I have: does this discrepancy also affect the odometer? ------ Karl 1981 Westy "Jenny" 2000 VW Jetta GLS VR6 Wilmington, DE |
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