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Old 12-12-2018, 09:58 AM   #9 (permalink)
EcoModding Lurker
Join Date: Sep 2011
Location: Michigan
Posts: 5

Little Car - '17 Toyota Yaris L

Mom Van - '16 Ford Transit T-350 HD Wagon XLT 12 Passenger
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Originally Posted by arcosine View Post
Every time I put larger diameter tires I see mpg improvement, fatter tires though, are harder to push through snow and slush, hydroplane easier.

I have 195/65R15 from the stock 175/70R14. Ive had 205/70R15 at one time, but used spacers. Car was not as stable at interstate speeds, but the spacers helped some. I liked how it cruised,lower rpm. Around town it would roll farther,no penalty.
Thanks for the real world experience arcosine.

If I crunch those numbers a bit I get the following info.

Stock tire size:
175/70-R14 = 23.65"

Stable Upsize:
195/65-R15 = 24.98" +5.64% +20mm width

Unstable upsize:
205/70-R15 = 26.30" +11.22% +30mm width

I would love to switch to a taller narrower tire with the same or higher weight rating. Unfortunately the selection of tires in that size let alone a tire I prefer are limited / non existent.

I will do more digging and see how much extra room there is in the wheel wells without adding a spacer.

I get my tires through discount tire. I will have to see if they will install larger tires than the listed stock.
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