First of all a big thanks to all the guys that came up with this mod. I found a used Kosman wheel last year and finally mounted up a new tire this past weekend. Very nice upgrade as I was able to put on the Avon Storm dual compound tire. So far I'm very impressed with the handling. I mounted the 160/70-17 tire which is a little taller than stock and noticed a slight lowering of engine rpm at cruising speed. Thats a welcome change too. I'm wondering about speedo calibration now. If the 160/70-17 tire is a little taller than stock, is my speedometer indicated speed closer to being accurate? Or is my indicated speed now further off? Thanks for any help, Mark

Speedo is driven by the front wheel..... 

  Thanks T-Cro, that makes perfect sense when you put it like that.

Thanks T-Cro, that makes perfect sense when you put it like that.

Thought so..... 

BTW I run a 120/70-17 on my ZRX front end and my speedo is only off by 2 MPH on the slow side..... The 130/70-18 tire mounted to the original wheel used to cancel out any speedo error before I made the swap.