On Wed, 25 Oct 2006, Phillip Batson wrote:
>
> hahaha! I think it just dawned on my why my avg mpg is around 12. I
> forgot that I had originally replaced the stock tires with 31x10.5x15
> tires. Bigger & wider = less mpg, right?
>
Don't forget to correct for the miles-per part of MPG. Your milage may
have suffered a bit, but if you went from the roughly 28" tallk 235/75r15
tires to the 31s and have not changed anything to correct for the diameter
difference, that 12MPG is really 13.3. Perhaps not accurate in either
case since stock speedometers are often "off" but still useful for your
own comparisons to old numbers.
In my mileage spreadsheets I always have a "correction factor" column that
gets me from odometer miles to real miles, as compared to my GPS. My
Dakota is spot on since I can tweak the speedometer with my SuperChips
programmer - I think over 100 GPS miles I register 100.1 miles on the
odometer. My Jetta gives me 97.3 miles for every 100 actual miles, so my
calculated MPGs are low if I use the odo numbers. My RamCharger has had 3
or 4 different size tires on it and I've never changed the speedo gear, so
I have 3 or 4 different "generations" of correction factors in there....
the tires don't make as much of a difference in MPG as you might expect
them to until you get to the extremes (like 40s with 4.10 gears around
town)
-- +-- Mike Maskalans ---------------- Rochester, NY ----------+ | '98 Dakota CC, SAS on 40s '84 RamCharger 4x4, plow truck | | '02 Jetta TDI 5sp, daily '97 Intrepid, not on the road | +-------------------- <http://mike.tepidcola.com/trucks/> --+
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