Quote:
Quote:
185/65-14...23.5" OE size
195/60-15...24.2" OE size
205/50-16...24.2" OE size
215/45-17...24.6" OE size
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Does ford change the calibration on the speedo depending on what size they install? Or is 'close enough' good enough?
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The correct overall diameter of wheel/tire combination is calculated as follows:
e.g. 205/50-16 is 205 mm. tire width with an aspect ratio of 50% of the tire width or 102.5 mm. multiplied by 2, thus resulting in 205 mm. and then added to the 16" diameter in mm. which is 406.4, giving you a total overall diameter of of 611.4 mm. or 24.07"
[[185*65%]*2] + [14*25.4] >> [120.25*2] + 355.6 >> 240.5 + 355.6 = 596.1 mm. -or- 23.468 in.
[[195*60%]*2] + [15*25.4] >> [117.0*2] + 381.0 >> 234 + 381 = 615.0 mm. -or- 24.212 in.
[[205*50%]*2] + [16*25.4] >> [102.5*2] + 406.4 >> 205 + 406.4 = 611.4 mm. -or- 24.071 in.
[[215*45%]*2] + [17*25.4] >> [96.75*2] + 431.8 >> 193.5 + 431.8 = 625.3 mm. -or- 24.618 in.