Wheels/Tire Combo ?

Thu Nov 27 14:27:48 EST 2003


I arrived at my speedo result comparison based on this calculator, available at Ned's Intended Acceleration website:


A very crude method, but nonetheless effective for an "idea" of what the difference would be.  

Your suggestion is a good one, and in my state there are 5 mile check points on the interstate in various locations for just this purpose.  I will certainly have to cross check any differences when the wheels are finally bolted up.

  ----- Original Message ----- 
  From: Bernie Benz 
  Cc: 200q20V mailing list 
  Sent: Thursday, November 27, 2003 11:13 AM
  Subject: Re: Wheels/Tire Combo ?

  > From: "JOSEPH TICHY" <JOSEPHTICHY7448 at msn.com>
  > I entered a comparison of the stock tires and the 16's with 225-50-16 tires
  > and it appears to be a wash for the speedo:  60 stock will read 59.3.  [the
  > speedo reading will be 59.3 too for the A4 tire size of 215-55-16, which makes
  > sense seeing how the 225-50 series is merely a plus one over 215-55]
  And just how do you easily check the speedo readings with different tire

  A more considered method might be to check the odometer over a 5 mile
  roadside measured course.  You may well find that the stock tire size does
  not give the correct odometer reading, hence you can adjust your new tire
  size to correct this error.  Once you get this right, you can then measure
  the speedo time error over the same course at an indicated 60 MPH and
  calculate the % error.


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