[thebrad]

Originally Posted by blackjackel

After much much much study, research, and deliberation, the results of which can be found here ( http://ecomodder.com/forum/showthrea...ling-2813.html ) I have decided to get new wheels and tires. My tires have another 5,000 miles on em, 10,000 if I'm really really lucky.... so.. I will be doing the following:

from 15" wheels to 14" wheels.

Tire size from 195-65-15 to 185-70-14

I used this tire calculation site to calculate the changes in measurements, its not much at all: http://www.miata.net/garage/tirecalc.html

my odometer would be off by .9% (if it says i'm going 60 MPH i'll be really going 60.5 MPH)

Specification Sidewall Radius Diameter Circumference Revs/Mile Difference
195/65-15 5.0in 12.5in 25.0in 78.5in 807 0.0%
185/70-14 5.1in 12.1in 24.2in 76.0in 834 -3.1%

The new tire would be .4 inches or 10 millimeteres narrower, or approx 1.5 inches if you count all tires combined.

I'm going from a GoodYear integrity to BridgeStone B381
This is going from a rolling resistence of 0.00955 to a RR of 0.00615 or a difference of 0.00340 in rolling resistence!

I expect at least 5 more MPG, if not more.

Any thoughts?
__________________

Not possible, well it is "possible" but it's not worth it.
You cannot go "negative 1" on a 9th generation Toyota Corolla, unless you plan to only use 14s on the rears because the front discs won't allow for anything smaller than 15s. Even then it's really questionable because you're going to spend X amount of dollars on new 14x5" rims, then being unable to effectively rotate the tires you'll be going through tires a lot quicker. I don't think it will pay itself off fast enough to warrant the headaches.