EVDL Administrator wrote:
It's absolutely true that the oversized spoked alloy wheels fitted to modern
cars are suboptimal for efficiency, both for weight and aero reasons.
The numbers back this up. Wider tires have higher rolling resistance,
more wind resistance, and weigh more. These all increase the energy cost.
The change in "gear ratio" due to tire diameter probably doesn't have
much effect on efficiency. It might move in the direction to be slightly
more efficient; or less efficient. But you do have to take the changes
in odometer readings into account.
A friend of mine bought a used car that came with very wide "wagon
wheel" style tires. He didn't like the looks or ride quality. So he
replaced them with plain old steel rims and the proper size tires.
The ride was much better, but he was surprised that the gas mileage went
up 2 mpg. That was a 10% improvement (from 20 to 22 mpg).
He also weighed the old tires and aluminum wheels, and found that they
were each 7 lbs heavier than the steel rims and tires.
By and large, vehicle "design" (styling) aims for the amygdala, not the
anterior cingulate cortex. That's one thing wrong with vehicle design.
Interesting way to put it. :-)
Lee Hart
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
-- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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