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Old 06-13-2014, 02:22 PM   #125 (permalink)
Thenorm
EcoModding Apprentice
 
Join Date: Oct 2013
Location: Canada
Posts: 132

The Rental - '13 Hyundai i30
90 day: 37.55 mpg (US)

Autocross - '04 Ford Focus ZX3
90 day: 24.76 mpg (US)

The Wifes - '02 Ford Focus SVT
90 day: 23.54 mpg (US)
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Quote:
Originally Posted by NeilBlanchard View Post
All else being equal, a large(r) diameter narrower tire will have lower rolling resistance and lower aero drag than a small(er) diameter wider tire.

One reason is that a larger diameter tire will 'bridge' across unevenness of the road better. Another is that since a tire is essentially 'wedging' the weight of the car uphill constantly - a larger diameter tire has a mechanical advantage, because the 'wedge' it provides is a lower angle.
just noticed this post.

a larger diameter tire actually has worse mechanical advantage when driving over a bump. the lever arm is longer, so it take more torque to do the work.
i'm not sure all the math, but my physics professor did this exact example in class once, and I've remembered it to this day.
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