MPG calculation: Help needed please

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Mar 6, 2004 | 04:33 PM

#21

mike_d

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Joined: Aug 2003

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From: Mountains outside of Boulder

Quote:

Originally Posted by hypnotoad

How much do you subtract, and at what rate, for the wear of the tires themselves? They aren't the same diam when they're worn as when new. In other words, it ain't accurate to begin with so all this math is like tuning up the band while the ship is sinking - fruitless.

yeah, but it's not that bad because the change in tire diameter isn't much. for example, let's say we have those 265's tires with 1/2" of tread (1/2" sounds about right, anyone have better guesses for the average tread?) i believe that the limit of legal tires is 2/32 tread. so our tire loses 14/32 of tread from both the top and bottom.

new tire = 31.6"
old tire = 31.6"-28/32" = 30.725"

30.725/31.6 = .972 or about a 3% change over the entire life of the tire if you run it to the legal limit.