Last summer, i wore out the 155/70-12 that came with my Mtero
So for the front i got 50psi 185/70-14 24.2"D +21% more Circumference than 145/70-12. But they rub on bumpy turns.
On the rear i put some free 35psi 185/60-14 . They noticeably drag!
I did some calculating (see below) and looking around i found
TOYO 310 - 155/80R14 80S TL £25.80, $42, speed S, load 80
This tire has low drag (155mm)
and 23.8"D which is +19% greater than original circumference and MPG.
speedo and odo will show 19% lower than actual.
I got used to that. Anyway I seldom exceed the speed limit!
likely will not rub, since my 24.2"D slightly does only on bumpy turns.
i will be checking to see if Toyo dealers here can get it for my fronts at least.
(I have torture tested Toyo Proxy on the track for over 100 mi and up to 150 mph. Great grip. Likely a dif. compound but they made a good tire.)
got these numbers using
http://www.miata.net/garage/tirecalc.html originally 145/70-12 20.0"D 62.8"Circumference
FRONT - FOR MPG
185/70-14 24.2"D +21% more Circumference -- RUBS on bumpy turns.
155/80-14 23.8"D +19% TOYO 310 - 155/80R14 80S TL £25.80=$42, speed S, load 80
175/70-14 23.6"D +18.3%
195/55-15 23.4"D +17.3%
155/80-13 22.8"D +14% Firestone, Cooper or Hancook or Kumho $48+
165/80-14 22.4"D +12%
195/60-14 23.2"D +16.1%
165/70-14 23.1"D +15.5%
155/70-14 22.5"D +13%
165/80-14 22.4"D +12%
REAR - FOR LOW DRAG
155/80-12 21.8"D +9% Kumho Power Star 758 155/80R12 400AB 35psi $43+15or172+35
165/70-12 21.1"D +5.5%
155/70-12 20.5"D +2.8%
Here is a ranked list of tires with Low_rolling_resistance:
http://en.wikipedia.org/wiki/Low_rollin ... ance_tires