"Donut" <Donut@donut.net> wrote in message
news:qc1ss1hls99an4e3bj7vd3rv6ic5bknr7g@4ax.com...
> <top posting only because the auto student is>
>
> pkurtz,
>
> You are taking my examples *way* to literally. The reason I put
> "normal driving conditions" in quotes is because I know there is no
> such thing. How about average driving conditions? You know, that
> state it which the vehicle is most often driven, that work for you?
>
> And when I referred to the three wheeler's, that was just another
> example. So no, I wont be able to provide an identical car on the road
> that you ask for. That was never my intention.
>
> Your argument still falls flat (no pun intended) to me.
>
> Harder tires (more inflation) equals better milage. Softer tires (less
> inflation) equals worse milage. On average.
>
> To take it to some extremes. If you are driving on ice, then an under
> inflated tire may increase your milage, as it provides a bigger
> footprint, thus more traction, and without traction, you'd be
> slipping. Of course your milage would be way worse than normal, but
> you might be able get somewhere.
>
> On the other hand, if you are driving around in a place with little
> precipitation, let alone the frozen kind, then a smaller footprint
> would be good for your milage, and you *can* achieve this by
> overinflating your tires.
>
> Not saying you should, mind you, you do have to factor in the altered
> wear. Higher risk of puncture, and most likely shortened life of the
> tires. And of course, less foot print equals less effective braking.
>
> I really just don't buy your argument that there would be significant
> "slip". If your driving so fast that your vehicles tires are leaving
> the road surface, then you aren't too worried about milage I'd guess
> :) And even at moderate speeds, wouldn't inertia negate most of the
> alleged "slip"?
>
> You used the word "exponentially" twice. As that is a mathematical
> term, and you are an auto student, I suppose you could produce the
> study or research that provides those numbers. You probably have
> easier access than I would, so I'd appreciate seeing them, or links
> to them.
>
> And if you're curious about the comment I put at the top of this post
> in <>'s... http://en.wikipedia.org/wiki/Top-posting
>
> Don
>
Don,
I appologize for top posting. I was unaware that it was a problem. The
reason I do it that way is because I believe that it makes for an easier
read, and if people are keeping current with the issue at hand, then it
should not be a problem. I understand that some older generations of Usenet
users won't like this, but I am not from that generation; however I try to
have consideration for others, so I hope this is better.
As to your comment about research being easier for me to come up with,
well if I talk with my instructors then I am sure they can give me all the
material I need. However, thanks to the WorldWideWeb, the information that
you seek is at the hands of anyone with a computer. I just did a search five
minutes ago on "gas mileage research" and it came up with about a thousand
hits, and on the second one I looked at it actually said to follow
manufacturers specifications for tire inflation, both quoting over-inflation
and under-inflation as a source of fuel mileage loss. Keep in mind when
doing web searches though, some common sense applies, and websites that end
in .net or .org will tend to be the more trusted sites to have "good"
information. The sites that end in .com are usually commercially based, and
usually say things so that they can sell a product.
As for producing the research I have read, I would have to go back 10yrs
to compile everything. I have picked up various bits of information by
reading material produced at shops that I have worked at, and through
information produced in the classes I have taken.
Also, as you said "taking my examples *way* to literally". I can only
base my arguments on the "facts" which are given to me, and back up my
arguments based on that. If you had come up with different, more real world,
examples. Then I would have analyzed your argument and put it up against
what I have been taught, and read over the years. Then I would have either
agreed, or dismissed your argument and provided the information as to why.
Here are some links that I picked up off the net for you. I realize that the
first one ends in .com, but I think we can all trust CNN.. LOL
http://money.cnn.com/2005/09/01/Auto...s_saving_test/
http://en.wikipedia.org/wiki/Miles_per_gallon I had a feeling you would
like this site, since you already used to inform me of my top posting.
Hope these fine useful. I did notice that only first one said anything about
over-inflating your tires. Anyway, have a good one, I have to get started on
a head gasket job now..
>
>
>
>
> On Tue, 17 Jan 2006 12:03:44 -0600, "pkurtz2" <pkurtz2@cox.net> wrote:
>
>>Don,
>>I hear what you are saying, but lets look at a couple of other things. You
>>say "Under "normal driving conditions"?" and in return I say "What do you
>>consider normal driving conditions?" When you look at the fuel ratings on
>>car stickers, you get the milage that the car would get under "Normal
>>Conditions", but there is NO SUCH THING. If you look in the owners manual
>>on
>>every car manufactured and read what normal driving conditions are, you
>>will
>>find they dont exist. There is no place on earth that one can find
>>"normal"
>>driving conditions. Now when you talk about the amount of slip on the tire
>>from an overpressurized tire then you have to take into account several
>>factors. Some of these would be speed, wind direction, wind speed, drag,
>>weight of the vehicle, etc, etc.... If you look at the electric cars that
>>race, the reason they only have 3 wheels is becuase they are extremely
>>light, and are balanced according to their design, this also helps cut
>>down
>>on drag. If you can point out ONE electric (completely Electric) car on
>>the
>>road today that is IDENTICAL to one of the cars that has raced in one of
>>those races then I will bow down, but I dont think you will. You will also
>>notice that those cars are designed to have no drag on them. Cars require
>>a
>>certain amount of tire on the road to prevent slip, to the amount allowed
>>by
>>the car designer because of the factors I have listed above, Especially
>>when
>>it comes to trucks. The other thing you have to look at when it comes to
>>trucks, is that the drive wheels are on the rear of the vehicle, not the
>>front. This reduces the amount of down force on the drive tires, and
>>increases the amount of slip exponentially. So if you overinflate your
>>tires, especially on the rear of a truck, then you have increased the
>>amount
>>of slip exponentially. The major problem with this is that roads are not
>>perfectly flat, thats why we have shock absorbers and moveable suspension,
>>and when you hit a bump, the rear of the vehicle comes down at a slower
>>rate
>>than the front. This increases the amount of time that the front
>>(non-driven) wheels are on the ground, and the rear of the vehicle is in
>>the
>>air.. Now if you reduce the amount of air in the rear tires, to specified
>>pressure, then the tires do part of the shock absorbers job, and thus the
>>rear tires stay in contact with the ground more, and have less slip.
>>
>>I hope this answers any questions you have.
>>
>>p.s. there is also slip created from the mechanical drag caused by the
>>front
>>wheel bearings, brakes, 4X4(if applicable), the rear wheels have to push
>>all
>>this, and overinflating them will also shorten tire life as well as reduce
>>gas milage.
>>
> <snip>
