actually... that someone was right. that's exactly what it means.
a 225/40/17 is 225mm wide, has a 90mm sidewall (225mm * .40), and mounts on a 17" rim. to get the "theoretical" outside diameter you'd take 90mm * 2 + 17" = 24.08"
it's better to check the tire makers specs. a smaller than stock tire will reduce your top speed but increase your acceleration and increase engine speed required for any given cruising speed. a larger than stock tire will increase your top speed and decrease engine speed for cruising, but significantly reduce accceleration. BOTH will cause your speedometer and odometer to be inaccurate.
i've been riding on 215/40/17 potenza s-02 and s-03s for a good amount of time now, on pretty bad city streets, and haven't had any problems yet except a flat (and ruined) tire. however, i am very careful of speed going over speedbumps, potholes, cracks/crevice, and those 1.5" thick metal plates that the sf dpw loves to liberally sprinkle on bad streets.
Quote:
Originally posted by Extreme_172001
thanks! Someone told me the 40 meant that the sidewall was 40% of the width of the tire. That wouldn't make much sense...
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