[V8] Efficiency and tires (was: Lower Emissions)

[Ed Kellock]

For my recent trip out to LA and towing a trailer back, I chose tires based
on efficiency.

(I have about 6 different sets between two V8's to choose from and yes, my
garage (and living room) sometimes look like a tire store).

Anyway, I wanted something with more snow/ice capability than regular
all-seasons and I wanted to err on the side of efficiency so I
chose the 205/60-15 Nokian NRW's mounted on a set of standard flat-faced V8
wheels.

Now I fretted over load ratings for a couple of days becasue I knew I was
going to be returning with lots of stuff in car and trailer and was almost
ready to change them out for another set even the morning of my departure,
but something prompted me to call my father, a retired Air Force Colonel who
was a C130 Loadmaster in the VietNam era.  He helped me break it down fairly
simply and after looking at the GVW on the door sill plate and a refresher
on proper trailer weight distribution and tongue weights, we decided that
the 205's would be fine.  And they were.

I mention all this because I recall a reply to my original trip report email
which commented that my MPG was pretty good while towing the trailer.  I
thought so too.  I had the tires at 42 psi cold all the way around and made
sure the trailer tires were at their recommended 45 psi.

The point to take away here is that tire size is tied to tire weight,
rolling mass, and in the realm of aerodynamics, frontal area.  Tire pressure
is a separate but equally important function of efficiency.

Remeber that the first type 44 that had the best coefficient of drag of its
time had really narrow tires and virtually non of the fancy flaring of the
'91 200 20v's or our V8's.  I think it was rated at .28 or something.  Still
a respectable rating today, I think.

Ed
Colorado Springs

On 12/16/05, dsaad at icehouse.net <dsaad at icehouse.net> wrote:
>
> That works out to 20.4 MPG - which is better than I have ever gotten with
> my
> 5-speed in comuter driving.
>
> I actually think that the automatics get better mileage for some odd
> reason.
>
> The only other things I could think of would be a dead on alignment, and
> maybe a
> narrower tire (tyre to you :-) to get your rolling resistance down.
> You might also experiment with different brands of gas. I seem to get
> better
> mileage with lower octane fuel. I am currently running 87 RON and am
> getting
> around 16 MPG. Considering it has been anywhere from 5 to 30 degrees F
> here for
> the last few weeks, that is not bad. I have to try really hard to get 19
> MPG in
> warmer weather.
>
> btw, I also have the radiator mostly blocked off to get the motor up to
> temp
> quicker. This seems to help a lot in the cold.
>
> Quoting Paul Jager <pjager at telus.net>:
>
> > I'm doing my best to see how low I can go.
> >
> > New o2 sensor
> > 0W15 oil (this is an energy saver)
> > Tires at 42 PSI all round
> > Brake pins and guides well lubed
> > (Parking brake tends to stay on slightly so it is out of use)
> >
> > Shift to N to coast as much as possible (not sure if I should keep doing
> > that) Keep in garage to stay warm. An inline heater would be a good
> addition.
> > And finally never stand idle - even shutdown at long lights.
> >
> > Past few days I've averaged 12.5 l/100km combined driving.  It's 4.21993 Auto.
> >
> > Any other ideas??
> >
> >
> > Paul Jager
> > www.jageng.com