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Old 03-24-2011, 03:05 PM   #76 (permalink)
mystere485
Barges Ahoy!
 
Join Date: May 2009
Location: canada
Posts: 26

The Black Car - '93 Honda Civic Del Sol si
90 day: 33.68 mpg (US)

The Benz - '70 Mercedes-Benz 220d
90 day: 33.13 mpg (US)

acura - '98 acura EL Premium
90 day: 29.91 mpg (US)
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Quote:
Originally Posted by Joenavy85 View Post
you really need to read up on the specs of tires. from above: 245 and 255 are the width of the tire(in mm). the 45 is the sidewall/width ratio (there is another word for it that is currently slipping my mind) that shows that the sidewall measurement is 45% of the width. if you narrow the width and keep the same ratio you change the sidewall measurement as well.

245mm x .45 = 110.25mm

255mm x .45 = 114.75mm

very slight difference, but still not the same height
Ok, that makes sense, however at 10.1 revs per mile and .35 of an inch difference that there will be a noticable change in ride height and mileage?

245/45R18
Rim Width Range: 7.5 - 9 in
Overall Diameter: 26.68 in 677.67 mm
Sidewall Height: 4.34 in 110.23 mm
Radius: 13.34 in 338.83 mm
Circumference: 83.81 in 2128.7 mm
Revs per Mile: 779.6

255/45R18
Section Width: 10.03 in 255 mm
Rim Diameter: 18 in 457.2 mm
Rim Width Range: 8 - 9.5 in
Overall Diameter: 27.03 in 686.56 mm
Sidewall Height: 4.51 in 114.55 mm
Radius: 13.51 in 343.15 mm
Circumference: 84.91 in 2156.7 mm
Revs per Mile: 769.5
Speedometer Difference: 1.312% too slow
Diameter Difference: 1.3%

Last edited by mystere485; 03-24-2011 at 03:25 PM..
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