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Jagdpanzer · 01-22-2012

I found this tool handy when I switch over to 19" wheels and larger diameter tires on the rear:
http://www.rimsntires.com/specs.jsp

Prior I was running stock 17" wheels and tires, 4.10 rear gears and 13/43 speedo correction gears. With this combo the speedometer and GPS more or less matched. However, after changing to 19" wheels and larger diameter 345/30ZR19 tires the speedometer showed 4 mph slower with 60 mph indicated on the GPS. Changing to 13/41 speedo gears narrowed the difference to around 1 mph which I find acceptable.

01-22-2012	#12
Jagdpanzer Join Date: Apr 2007 Location: Northern VA Posts: 2,649	Re: Differential calc I found this tool handy when I switch over to 19" wheels and larger diameter tires on the rear: http://www.rimsntires.com/specs.jsp Prior I was running stock 17" wheels and tires, 4.10 rear gears and 13/43 speedo correction gears. With this combo the speedometer and GPS more or less matched. However, after changing to 19" wheels and larger diameter 345/30ZR19 tires the speedometer showed 4 mph slower with 60 mph indicated on the GPS. Changing to 13/41 speedo gears narrowed the difference to around 1 mph which I find acceptable. __________________ Phil Wasinger 1994 Torch Red ZR-1 WAZOO Member George Braml Intake Last edited by Jagdpanzer; 01-22-2012 at 12:29 PM. Reason: Corrected 13/41 speedo gears