[Crazirich]

NOS2Go4Me,Aug 29 2005, 10:23 AM Wrote:I think the ECU can flip back and forth between each of the standard Focus tire sizes (overall diameter). The 185/65R14 is standard for the 14" crowd, and would fit nicely with no clearance issues.

I say the ECU adapts because I've moved to the 16s and the overall diameter size is slightly larger, yet I've paced a few cars and I seem to be right bang-on for the speed reported by the speedo.
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There is nothing the computer learnes from changing tires if you switch between stock tire size P185/65R14 (23.5" diameter), P195/60R15 (24.2" diameter), P205/50R16 (24.1" diameter). Its the diameter size that screws you up if you can stay around the 24" mark you are fine and won't notice anything, might mess you like 1.5km/hr. Its like changing a gear size, smaller = faster; bigger = slower

I messed around with this alot on my old stang burning up left over tires at home and learned alot.