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Old 01-29-2010, 04:35 PM   #3 (permalink)
MetroMPG
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,530

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 54.46 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car Mirage - '14 Mitsubishi Mirage ES (base)
90 day: 62.14 mpg (US)
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Quote:
Originally Posted by 90crxHF View Post
I know this is going to be very hard to do considering the 70MPH speed.
You said it!

Quote:
do you guys think switching from a 195/50/15 to a 185/70/14 would be a wise choice?
Did you check the circumference difference?

This tool shows you'd raise your effective gearing slightly, since the diameter of the 175 is larger.

And the narrower the tire, the better, in terms of aero drag. See here: http://ecomodder.com/forum/showthrea...g-cd-7475.html

You'd raise the ride height slightly, which is probably bad for drag.

But the smooth wheel cover would be a plus.

And even at the same pressure, two tires could have vastly different rolling resistance.

So... it's not easy to say for sure, but I'd do it.

(Actually, I'd do what Ben did on his CRX: put smooth alloys with the even narrower Insight tires on: http://ecomodder.com/forum/showthrea...ghts-9517.html )
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Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



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www.MetroMPG.com - fuel efficiency info for Geo Metro owners
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