Marcus Reddish via EV wrote:
As for losing 10 mpg by switching to different LRR tires, I bet $50 they
had the pressure at 32psi front, 28 psi back. That is only way to lose 10
mpg. Two different LRR tires might be 1-3 mpg different, not 10 mpg!
Part of the problem is that LRR is too often just marketing doubletalk
-- it doesn't mean anything. Tire companies know what the rolling
resistance is; but they certainly don't want consumers to get their
hands on the data. They might base their purchases on (gasp! choke!)
objective facts rather than advertising, appearance, and price! :-O
The automakers really *do* care about LRR, because it helps them meet
government mandated fuel economy standards and sell cars. They test
tires themselves, and demand performance from the tire companies. As a
result, the tire on a new car has better rolling resistance than the
same (apparently) identical tire from a tire store. You can tell if they
are different by the DOT code on the tire, which identifies who and
where it was actually made.
You are absolutely correct that many car service people routinely
underinflate tires, and often blindly use 32psi no matter what the
vehicle calls for.
On a 10mpg difference due to tires: That can easily happen with a
high-mpg vehicle like the Insight. A 10 mpg drop (from 60mpg to 50mpg)
is a 17% drop. The same 17% drop on a 15 mpg vehicle would only reduce
it by 2.5 mpg (to 12.5 mpg).
PS: Interesting info on the truck tires. Thanks! :-)
--
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's EV projects are at http://www.sunrise-ev.com/LeesEVs.htm
_______________________________________________
UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
http://lists.evdl.org/listinfo.cgi/ev-evdl.org
For EV drag racing discussion, please use NEDRA
(http://groups.yahoo.com/group/NEDRA)
