On Thu, Sep 10, 2009 at 11:07 AM , Kim Brennan wrote:

If you look at almost all the high fuel
> economy vehicles, one thing they'll have in common is small diameter
> tires.

So, a few years ago almost all small cars (Corola and similar) had 13
inch wheels with something like 165-80 tires.  small wheel, high aspect
ratio tire.  Now they typically have (at least my Prius does) 15 inch
wheels, with 185-65 tires.  Bigger wheel, thinner tires.  In part, I
thought this might be a part of the current fad toward thin tires big
wheels, but somehow I doubt that Toyota in designing the Prius went that
way -- My general thoughts are that Toyota tried to maximize fuel
efficiency without sacrificing safety.

So far as vanagon content -- I still have the original 14 inch wheels,
and run 195-75 tires.  This is slightly wider but not significantly so
than the original 185s, same aspect, so a tad taller too.  Am I
sacrificing, gaining, or is it a wash?  I get about 22 mpg on long
drives, unless I get on the interstate and the traffic is so heavy that
I feel compelled to try to keep up to keep from getting run over -- in
which case I try to get off onto a more sensible road as soon as
possible.

Dave Mc