texascavers Digest 1 Aug 2012 12:33:31 -0000 Issue 1601
Topics (messages 20438 through 20449):
Geological Society of America Convention: abstracts due in two weeks!
20438 by: George Veni
KWI Carbon and Boundaries in Karst Symposium: website and registration open!
20439 by: George Veni
Re: Final Revised TSA Members List
20440 by: Carl Kunath
Help - speed, tire size change
20441 by: Mimi Jasek
20442 by: Carl Kunath
20443 by: Nico Escamilla
20444 by: Diana Tomchick
20445 by: Diana Tomchick
20447 by: Mimi Jasek
20448 by: vivbone.att.net
20449 by: philipmoss.juno.com
Speeding and Your Vehicle's Mileage
20446 by: Diana Tomchick
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--- Begin Message ---
Dear Friends,
The next Geological Society of America Convention will be held this year in
Charlotte, North Carolina on 4-7 November. The call for abstracts has gone
out. The deadline for submissions is only two weeks away: 14 August. Six
sessions on caves and karst are offered this year, plus one specifically
requesting cave and karst papers within its broader topic. Given the
convention's location, four of the sessions are focused on eogenetic karst
settings. Several related sessions that would be excellent venues for karst
papers are also being offered on topics that include biology, archeology,
and hydrogeology. For details:
http://www.geosociety.org/meetings/2012/sessions/topical.asp.
The first three of the seven cave and karst sessions listed below are
sponsored or co-sponsored by the National Cave and Karst Research Institute:
T18. The Evolution of Karst Landscapes through Time in Response to Changing
Hydrologic, Geomorphic, and Tectonic Conditions
GSA Quaternary Geology and Geomorphology Division; GSA Hydrogeology
Division; National Cave and Karst Research Institute
Cory W. Blackeagle
How do the characteristics of karst terrain change in response to changes in
hydrology, geomorphology, and tectonism? How are these changes reflected in
the landscape and hydrogeology? Recent advances in methodology will also be
highlighted.
T92. Eogenetic Karst Aquifers: Water Resources and Water Quality
GSA Hydrogeology Division; GSA Environmental and Engineering Geology
Division; National Cave and Karst Research Institute
Lewis A. Land, Lee J. Florea
Eogenetic karst aquifers in coastal areas are particularly vulnerable to
natural and anthropogenic contamination. Papers are welcome on water
resource and water quality issues in such aquifers, as well as methods used
to characterize and remediate them.
T107. Comparisons of Flow and Chemistry in Eogenetic and Telogenetic Karst
Aquifers
GSA Hydrogeology Division; Karst Waters Institute; National Cave and Karst
Research Institute
Jason Gulley, Corinne Wong
This session seeks to understand how differences in porosity between
eogenetic (primary matrix porosity) and telogenetic (fractured matrix
porosity) karst systems influence the hydrological and geochemical processes
in karst aquifers, including cave formation.
T49. Geology in the National Forests and Grasslands-Stewardship, Education,
and Research
GSA Hydrogeology Division; GSA Geology and Society Division; USDA Forest
Service
Christopher P. Carlson, Michael A. Crump
This session will explore aspects of the geological sciences related to the
National Forests and Grasslands. Topics include paleontology, geomorphology,
hydrogeology, geoecology, natural-hazard mitigation, cave and karst
resources, and interpretive and recreational geology.
T95. Biscayne Aquifer
GSA Hydrogeology Division; GSA Geophysics Division
Michael C. Sukop, Dean Whitman, Virginia Walsh, Joseph D. Hughes, Jayantha
Obeysekera, Jefferson B. Giddings
We encourage presentations dealing with all aspects of the geology, physics,
chemistry, hydrogeology, geophysics, simulation, protection, and management
of the Biscayne Aquifer and its role in the water supply and ecology of
southeast Florida.
T155. The Heart of an Explorer: A Tribute to Ronald Greeley
GSA Planetary Geology Division
David A. Williams
Ronald Greeley, a leader in planetary geology, passed away in October 2011.
In tribute to Ron's memory, we are seeking presentations to discuss recent
results from the field or technique or missions, in which Ron participated.
[Ron pioneered the field of interplanetary cave research.]
T159. Surf's Up: New Insights on the Geology, Karst, and Paleontology of
Carbonate Systems of the Bahama Archipelago
GSA Hydrogeology Division; Eastern Section SEPM (Society for Sedimentary
Geology); Karst Waters Institute; Paleontological Society
H. Allen Curran, John E. Mylroie
Presentations demonstrating new dimensions of carbonates research within the
Bahama Archipelago (including Turks and Caicos) are encouraged. Emphasis on
shallow-marine sedimentology and emergent island geology, karst,
paleontology, geobiology, and geochemistry, with closely related topics will
be considered.
Feel free to distribute this message to anyone you think may be interested.
George
***************************
George Veni, Ph.D.
Executive Director
National Cave and Karst Research Institute
400-1 Cascades Avenue
Carlsbad, New Mexico 88220-6215 USA
Office: 575-887-5517
Mobile: 210-863-5919
Fax: 575-887-5523
gv...@nckri.org
www.nckri.org
--- End Message ---
--- Begin Message ---
Dear Friends,
Geology, biology, chemistry, hydrology, petroleum, climate change? If any of
these are your interest, I encourage you to attend the Karst Waters
Institute (KWI) Carbon and Boundaries in Karst Symposium on 7-11 January
2013. NCKRI is delighted to work with KWI and host this conference at NCKRI
Headquarters in Carlsbad, New Mexico, USA. For more details and to register,
go to www.nckri.org/kwi2013.
Please distribute this message to anyone you think may be interested.
I hope to see you there in January.
George
***************************
George Veni, Ph.D.
Executive Director
National Cave and Karst Research Institute
400-1 Cascades Avenue
Carlsbad, New Mexico 88220-6215 USA
Office: 575-887-5517
Mobile: 210-863-5919
Fax: 575-887-5523
gv...@nckri.org
www.nckri.org
--- End Message ---
--- Begin Message ---
Denise, thanks very much for your persistence and hard work on this membership
list and for your service to TSA in general. We are fortunate to have you
working for us.
===Carl Kunath
From: Denise Prendergast
Sent: Tuesday, July 31, 2012 6:58 PM
To: pepabe...@hotmail.com
Subject: Final Revised TSA Members List
OK, this is the last version I will be sending out this year. Enjoy!
Cheers,
Denise Prendergast
TSA Secretary
--- End Message ---
--- Begin Message ---
Ok, I need help. I have a Ford Escape that we use as our main caving vehicle
due to great gas mileage. Due to age, miles, and need for stronger sidewalls
and better traction, we traded our old tires for new. Love them, but because
bigger, noticed huge drop in gas mileage at same speeds used to traveling, and
I seem to be staying up with or passing everyone!!
Old = P235/70R16 normal street tires
New = LT245/75R16 E Toyo OPAT OWL 120Q
Don't want a speeding ticket, and need my good mpg back, or close to it. Can
anyone tell me how much to decrease my speed, and if the reduction is the same
for all speeds? If not the same, how much decrease at what increments?
I believe my old tires were 28" diameter (spare is that) with 7.33'
circumference, and new are 30" with 7.85' circumference.
I have to believe there are more than enough math wiz/ tire savvy folks out
there to get me some answers, but if I am asking the impossible, tell me. I do
have a tachometer as well as a speedometer if that helps.
For us, mpg means a lot due to cost of gas, and determines how many trips we
make. I would really appreciate any help anyone can give me.
Thanks,
Mimi Jasek
Sent from my iPhone
--- End Message ---
--- Begin Message ---
Mimi:
Yes, you are asking the impossible or close to it. Your larger tires
require more power and that means more fuel.
But be aware that you are now traveling faster than your speedometer
indicates as compared to your prior condition. That means more fuel.
How much is a "huge" drop in mileage?
Your new tires have a greater frontal area and are harder to move through
the atmosphere. They are also larger and that means that your engine RPM is
less at any given speed. It may be that you have fallen out of the designed
"power band" where your engine is at it's best efficiency. Your speedometer
will register less than your actual speed all the time. There are lots of
formulas and nearly as many methods for calculating your true speed. If you
have a measured stretch of miles in your area you can pass through at a
constant indicated 60 mph with a stopwatch and will likely find that you are
doing a mile is something less than a minute (who knows if your prior
calibration was accurate?). An easy way these days is to use your GPS.
They are very accurate and will calculate your real ground speed very
closely.
For the future, you might raise your tire pressure a few pounds (less
rolling resistance) and purchase a few shares of Exxon stock.
===Carl Kunath
--------------------------------------------------------------------------------
-----Original Message-----
From: Mimi Jasek
Sent: Tuesday, July 31, 2012 11:12 PM
To: TexasCavers
Subject: [Texascavers] Help - speed, tire size change
Ok, I need help. I have a Ford Escape that we use as our main caving vehicle
due to great gas mileage. Due to age, miles, and need for stronger sidewalls
and better traction, we traded our old tires for new. Love them, but because
bigger, noticed huge drop in gas mileage at same speeds used to traveling,
and I seem to be staying up with or passing everyone!!
Old = P235/70R16 normal street tires
New = LT245/75R16 E Toyo OPAT OWL 120Q
Don't want a speeding ticket, and need my good mpg back, or close to it. Can
anyone tell me how much to decrease my speed, and if the reduction is the
same for all speeds? If not the same, how much decrease at what increments?
I believe my old tires were 28" diameter (spare is that) with 7.33'
circumference, and new are 30" with 7.85' circumference.
I have to believe there are more than enough math wiz/ tire savvy folks out
there to get me some answers, but if I am asking the impossible, tell me. I
do have a tachometer as well as a speedometer if that helps.
For us, mpg means a lot due to cost of gas, and determines how many trips we
make. I would really appreciate any help anyone can give me.
Thanks,
Mimi Jasek
Sent from my iPhone
---------------------------------------------------------------------
Visit our website: http://texascavers.com
To unsubscribe, e-mail: texascavers-unsubscr...@texascavers.com
For additional commands, e-mail: texascavers-h...@texascavers.com
--- End Message ---
--- Begin Message ---
All engines have an "RPM sweet spot" so to speak, when you get past it your
fuel economy goes down.. To move the larger mass of bigger tires you need
more power which requires higher rpm and hurts your pocket, like Carl said
use your gps, I jumped from stock to 35" tires on my dodge and theres a
difference of 7 to 10 km/h between the ground speed on the gps and the one
shown on the dash of the truck. Some people resort to re-gearing the rear
differential to better move larger tires but that might be expensive.
Nico
On Tue, Jul 31, 2012 at 11:32 PM, Carl Kunath <carl.kun...@suddenlink.net>wrote:
> Mimi:
> Yes, you are asking the impossible or close to it. Your larger tires
> require more power and that means more fuel.
>
> But be aware that you are now traveling faster than your speedometer
> indicates as compared to your prior condition. That means more fuel.
>
> How much is a "huge" drop in mileage?
>
> Your new tires have a greater frontal area and are harder to move through
> the atmosphere. They are also larger and that means that your engine RPM
> is less at any given speed. It may be that you have fallen out of the
> designed "power band" where your engine is at it's best efficiency. Your
> speedometer will register less than your actual speed all the time. There
> are lots of formulas and nearly as many methods for calculating your true
> speed. If you have a measured stretch of miles in your area you can pass
> through at a constant indicated 60 mph with a stopwatch and will likely
> find that you are doing a mile is something less than a minute (who knows
> if your prior calibration was accurate?). An easy way these days is to
> use your GPS. They are very accurate and will calculate your real ground
> speed very closely.
>
> For the future, you might raise your tire pressure a few pounds (less
> rolling resistance) and purchase a few shares of Exxon stock.
>
> ===Carl Kunath
>
> ------------------------------**------------------------------**
> --------------------
>
> -----Original Message----- From: Mimi Jasek
> Sent: Tuesday, July 31, 2012 11:12 PM
> To: TexasCavers
> Subject: [Texascavers] Help - speed, tire size change
>
>
> Ok, I need help. I have a Ford Escape that we use as our main caving
> vehicle due to great gas mileage. Due to age, miles, and need for stronger
> sidewalls and better traction, we traded our old tires for new. Love them,
> but because bigger, noticed huge drop in gas mileage at same speeds used to
> traveling, and I seem to be staying up with or passing everyone!!
>
> Old = P235/70R16 normal street tires
>
> New = LT245/75R16 E Toyo OPAT OWL 120Q
>
> Don't want a speeding ticket, and need my good mpg back, or close to it.
> Can anyone tell me how much to decrease my speed, and if the reduction is
> the same for all speeds? If not the same, how much decrease at what
> increments?
>
> I believe my old tires were 28" diameter (spare is that) with 7.33'
> circumference, and new are 30" with 7.85' circumference.
>
> I have to believe there are more than enough math wiz/ tire savvy folks
> out there to get me some answers, but if I am asking the impossible, tell
> me. I do have a tachometer as well as a speedometer if that helps.
>
> For us, mpg means a lot due to cost of gas, and determines how many trips
> we make. I would really appreciate any help anyone can give me.
>
> Thanks,
>
> Mimi Jasek
>
>
>
> Sent from my iPhone
> ------------------------------**------------------------------**---------
> Visit our website: http://texascavers.com
> To unsubscribe, e-mail:
> texascavers-unsubscribe@**texascavers.com<texascavers-unsubscr...@texascavers.com>
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>
> ------------------------------**------------------------------**---------
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> To unsubscribe, e-mail:
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>
>
--- End Message ---
--- Begin Message ---
Mimi,
A simple back-of-the-envelope calculation would be to divide the current tire
circumference by the previous tire circumference. This would give you an
estimate of the fractional difference the new, larger tire would travel for
each revolution of the tire. Using the numbers you supplied gives a value of
approximately 1.071. If you are used to driving at 60 m.p.h., in theory the new
tires would actually be taking you at 60 x 1.071 = 64.26 m.p.h.
Of course this is a pretty simplistic estimate.
If you want to maximize your gas mileage, that's a more complicated experiment
that would need you to fill your gas tank (be sure to always use the same type
of gas--the higher the percentage of ethanol, the lower your mile per gallon),
drive a set distance at different speeds and re-fill the tank to see how much
you used. Oh, and be sure that the prevailing wind speed and direction is the
same every time you repeat the drive at the different speeds.
Diana
********************************************************
Diana R. Tomchick
Professor
Dept. of Biochemistry
University of Texas Southwestern Medical Center
5323 Harry Hines Blvd.
Dallas, TX 75390-8816
(214) 645-6383 (office)
(214) 418-5827 (cell)
diana.tomch...@utsouthwestern.edu
On Jul 31, 2012, at 11:09 PM, "Mimi Jasek" <mjca...@gmail.com> wrote:
> Ok, I need help. I have a Ford Escape that we use as our main caving vehicle
> due to great gas mileage. Due to age, miles, and need for stronger sidewalls
> and better traction, we traded our old tires for new. Love them, but because
> bigger, noticed huge drop in gas mileage at same speeds used to traveling,
> and I seem to be staying up with or passing everyone!!
>
> Old = P235/70R16 normal street tires
>
> New = LT245/75R16 E Toyo OPAT OWL 120Q
>
> Don't want a speeding ticket, and need my good mpg back, or close to it. Can
> anyone tell me how much to decrease my speed, and if the reduction is the
> same for all speeds? If not the same, how much decrease at what increments?
>
> I believe my old tires were 28" diameter (spare is that) with 7.33'
> circumference, and new are 30" with 7.85' circumference.
>
> I have to believe there are more than enough math wiz/ tire savvy folks out
> there to get me some answers, but if I am asking the impossible, tell me. I
> do have a tachometer as well as a speedometer if that helps.
>
> For us, mpg means a lot due to cost of gas, and determines how many trips we
> make. I would really appreciate any help anyone can give me.
>
> Thanks,
>
> Mimi Jasek
>
>
>
> Sent from my iPhone
> ---------------------------------------------------------------------
> Visit our website: http://texascavers.com
> To unsubscribe, e-mail: texascavers-unsubscr...@texascavers.com
> For additional commands, e-mail: texascavers-h...@texascavers.com
>
________________________________
UT Southwestern Medical Center
The future of medicine, today.
--- End Message ---
--- Begin Message ---
I would guess that the increase in mass of the tires has far less impact on the
increase in gas usage than the fact that the larger tire means that the vehicle
is traveling faster. The amount of drag associated with even a 5 mph increase
in speed at 60 mph would be plenty to cause a noticeable effect in reduced gas
mileage for an SUV-type vehicle such as a Ford Escape. We're not talking about
the world's most aerodynamic vehicle here, after all.
Diana
********************************************************
Diana R. Tomchick
Professor
Dept. of Biochemistry
University of Texas Southwestern Medical Center
5323 Harry Hines Blvd.
Dallas, TX 75390-8816
(214) 645-6383 (office)
(214) 418-5827 (cell)
diana.tomch...@utsouthwestern.edu<mailto:diana.tomch...@utsouthwestern.edu>
On Jul 31, 2012, at 11:41 PM, "Nico Escamilla"
<pitboun...@gmail.com<mailto:pitboun...@gmail.com>> wrote:
All engines have an "RPM sweet spot" so to speak, when you get past it your
fuel economy goes down.. To move the larger mass of bigger tires you need more
power which requires higher rpm and hurts your pocket, like Carl said use your
gps, I jumped from stock to 35" tires on my dodge and theres a difference of 7
to 10 km/h between the ground speed on the gps and the one shown on the dash of
the truck. Some people resort to re-gearing the rear differential to better
move larger tires but that might be expensive.
Nico
On Tue, Jul 31, 2012 at 11:32 PM, Carl Kunath
<carl.kun...@suddenlink.net<mailto:carl.kun...@suddenlink.net>> wrote:
Mimi:
Yes, you are asking the impossible or close to it. Your larger tires require
more power and that means more fuel.
But be aware that you are now traveling faster than your speedometer indicates
as compared to your prior condition. That means more fuel.
How much is a "huge" drop in mileage?
Your new tires have a greater frontal area and are harder to move through the
atmosphere. They are also larger and that means that your engine RPM is less
at any given speed. It may be that you have fallen out of the designed "power
band" where your engine is at it's best efficiency. Your speedometer will
register less than your actual speed all the time. There are lots of formulas
and nearly as many methods for calculating your true speed. If you have a
measured stretch of miles in your area you can pass through at a constant
indicated 60 mph with a stopwatch and will likely find that you are doing a
mile is something less than a minute (who knows if your prior calibration was
accurate?). An easy way these days is to use your GPS. They are very accurate
and will calculate your real ground speed very closely.
For the future, you might raise your tire pressure a few pounds (less rolling
resistance) and purchase a few shares of Exxon stock.
===Carl Kunath
--------------------------------------------------------------------------------
-----Original Message----- From: Mimi Jasek
Sent: Tuesday, July 31, 2012 11:12 PM
To: TexasCavers
Subject: [Texascavers] Help - speed, tire size change
Ok, I need help. I have a Ford Escape that we use as our main caving vehicle
due to great gas mileage. Due to age, miles, and need for stronger sidewalls
and better traction, we traded our old tires for new. Love them, but because
bigger, noticed huge drop in gas mileage at same speeds used to traveling, and
I seem to be staying up with or passing everyone!!
Old = P235/70R16 normal street tires
New = LT245/75R16 E Toyo OPAT OWL 120Q
Don't want a speeding ticket, and need my good mpg back, or close to it. Can
anyone tell me how much to decrease my speed, and if the reduction is the same
for all speeds? If not the same, how much decrease at what increments?
I believe my old tires were 28" diameter (spare is that) with 7.33'
circumference, and new are 30" with 7.85' circumference.
I have to believe there are more than enough math wiz/ tire savvy folks out
there to get me some answers, but if I am asking the impossible, tell me. I do
have a tachometer as well as a speedometer if that helps.
For us, mpg means a lot due to cost of gas, and determines how many trips we
make. I would really appreciate any help anyone can give me.
Thanks,
Mimi Jasek
Sent from my iPhone
---------------------------------------------------------------------
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---------------------------------------------------------------------
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________________________________
UT Southwestern Medical Center
The future of medicine, today.
--- End Message ---
--- Begin Message ---
Ok, Diana, Nico, and Karl, thanks so much. A lot of what you all said was close
to some of what I thought, but you defined it for me.
I will use your info to try to solve our problem, and for now just slow down.
Lost 5+ mpg, which to me is a lot, for the cookie jar has no funds for stock.
If others reply to help, it will be tomorrow before I get back to mail. Last
load of laundry calls to be put away, then this tired lady must go to sleep
before another work day starts:)
Mimi
Sent from my iPhone
On Jul 31, 2012, at 11:42 PM, Diana Tomchick
<diana.tomch...@utsouthwestern.edu> wrote:
> Mimi,
>
> A simple back-of-the-envelope calculation would be to divide the current tire
> circumference by the previous tire circumference. This would give you an
> estimate of the fractional difference the new, larger tire would travel for
> each revolution of the tire. Using the numbers you supplied gives a value of
> approximately 1.071. If you are used to driving at 60 m.p.h., in theory the
> new tires would actually be taking you at 60 x 1.071 = 64.26 m.p.h.
>
> Of course this is a pretty simplistic estimate.
>
> If you want to maximize your gas mileage, that's a more complicated
> experiment that would need you to fill your gas tank (be sure to always use
> the same type of gas--the higher the percentage of ethanol, the lower your
> mile per gallon), drive a set distance at different speeds and re-fill the
> tank to see how much you used. Oh, and be sure that the prevailing wind speed
> and direction is the same every time you repeat the drive at the different
> speeds.
>
>
> Diana
>
> ********************************************************
> Diana R. Tomchick
> Professor
> Dept. of Biochemistry
> University of Texas Southwestern Medical Center
> 5323 Harry Hines Blvd.
> Dallas, TX 75390-8816
> (214) 645-6383 (office)
> (214) 418-5827 (cell)
> diana.tomch...@utsouthwestern.edu
>
> On Jul 31, 2012, at 11:09 PM, "Mimi Jasek" <mjca...@gmail.com> wrote:
>
>> Ok, I need help. I have a Ford Escape that we use as our main caving vehicle
>> due to great gas mileage. Due to age, miles, and need for stronger sidewalls
>> and better traction, we traded our old tires for new. Love them, but because
>> bigger, noticed huge drop in gas mileage at same speeds used to traveling,
>> and I seem to be staying up with or passing everyone!!
>>
>> Old = P235/70R16 normal street tires
>>
>> New = LT245/75R16 E Toyo OPAT OWL 120Q
>>
>> Don't want a speeding ticket, and need my good mpg back, or close to it. Can
>> anyone tell me how much to decrease my speed, and if the reduction is the
>> same for all speeds? If not the same, how much decrease at what increments?
>>
>> I believe my old tires were 28" diameter (spare is that) with 7.33'
>> circumference, and new are 30" with 7.85' circumference.
>>
>> I have to believe there are more than enough math wiz/ tire savvy folks out
>> there to get me some answers, but if I am asking the impossible, tell me. I
>> do have a tachometer as well as a speedometer if that helps.
>>
>> For us, mpg means a lot due to cost of gas, and determines how many trips we
>> make. I would really appreciate any help anyone can give me.
>>
>> Thanks,
>>
>> Mimi Jasek
>>
>>
>>
>> Sent from my iPhone
>> ---------------------------------------------------------------------
>> Visit our website: http://texascavers.com
>> To unsubscribe, e-mail: texascavers-unsubscr...@texascavers.com
>> For additional commands, e-mail: texascavers-h...@texascavers.com
>>
>
> ________________________________
>
> UT Southwestern Medical Center
> The future of medicine, today.
--- End Message ---
--- Begin Message ---
Another reason you're mileage will drop is that the increased tire diameter
will raise you slightly higher relative to the ground, which will increase your
wind resistance. Wind resistance is the main reason mileage drops so fast at
higher speeds too.
-Vivian Loftin
--- On Wed, 8/1/12, Mimi Jasek <mjca...@gmail.com> wrote:
> From: Mimi Jasek <mjca...@gmail.com>
> Subject: Re: [Texascavers] Help - speed, tire size change
> To: "Diana Tomchick" <diana.tomch...@utsouthwestern.edu>
> Cc: "TexasCavers" <texascavers@texascavers.com>
> Date: Wednesday, August 1, 2012, 12:01 AM
> Ok, Diana, Nico, and Karl, thanks so
> much. A lot of what you all said was close to some of what I
> thought, but you defined it for me.
>
> I will use your info to try to solve our problem, and for
> now just slow down.
>
> Lost 5+ mpg, which to me is a lot, for the cookie jar has no
> funds for stock.
>
> If others reply to help, it will be tomorrow before I get
> back to mail. Last load of laundry calls to be put away,
> then this tired lady must go to sleep before another work
> day starts:)
>
> Mimi
>
> Sent from my iPhone
>
> On Jul 31, 2012, at 11:42 PM, Diana Tomchick
> <diana.tomch...@utsouthwestern.edu>
> wrote:
>
> > Mimi,
> >
> > A simple back-of-the-envelope calculation would be to
> divide the current tire circumference by the previous tire
> circumference. This would give you an estimate of the
> fractional difference the new, larger tire would travel for
> each revolution of the tire. Using the numbers you supplied
> gives a value of approximately 1.071. If you are used to
> driving at 60 m.p.h., in theory the new tires wouldÂ
> actually be taking you at 60 x 1.071 = 64.26 m.p.h.
> >
> > Of course this is a pretty simplistic estimate.
> >
> > If you want to maximize your gas mileage, that's a more
> complicated experiment that would need you to fill your gas
> tank (be sure to always use the same type of gas--the higher
> the percentage of ethanol, the lower your mile per gallon),
> drive a set distance at different speeds and re-fill the
> tank to see how much you used. Oh, and be sure that the
> prevailing wind speed and direction is the same every time
> you repeat the drive at the different speeds.
> >
> >
> > Diana
> >
> >
> ********************************************************
> > Diana R. Tomchick
> > Professor
> > Dept. of Biochemistry
> > University of Texas Southwestern Medical Center
> > 5323 Harry Hines Blvd.
> > Dallas, TX 75390-8816
> > (214) 645-6383 (office)
> > (214) 418-5827 (cell)
> > diana.tomch...@utsouthwestern.edu
> >
> > On Jul 31, 2012, at 11:09 PM, "Mimi Jasek" <mjca...@gmail.com>
> wrote:
> >
> >> Ok, I need help. I have a Ford Escape that we use
> as our main caving vehicle due to great gas mileage. Due to
> age, miles, and need for stronger sidewalls and better
> traction, we traded our old tires for new. Love them, but
> because bigger, noticed huge drop in gas mileage at same
> speeds used to traveling, and I seem to be staying up with
> or passing everyone!!
> >>
> >> Old = P235/70R16 normal street tires
> >>
> >> New = LT245/75R16 E Toyo OPAT OWL 120Q
> >>
> >> Don't want a speeding ticket, and need my good mpg
> back, or close to it. Can anyone tell me how much to
> decrease my speed, and if the reduction is the same for all
> speeds? If not the same, how much decrease at what
> increments?
> >>
> >> I believe my old tires were 28" diameter (spare is
> that) with 7.33' circumference, and new are 30" with 7.85'
> circumference.
> >>
> >> I have to believe there are more than enough math
> wiz/ tire savvy folks out there to get me some answers, but
> if I am asking the impossible, tell me. I do have a
> tachometer as well as a speedometer if that helps.
> >>
> >> For us, mpg means a lot due to cost of gas, and
> determines how many trips we make. I would really appreciate
> any help anyone can give me.
> >>
> >> Thanks,
> >>
> >> Mimi Jasek
> >>
> >>
> >>
> >> Sent from my iPhone
> >>
> ---------------------------------------------------------------------
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> >>
> >
> > ________________________________
> >
> > UT Southwestern Medical Center
> > The future of medicine, today.
>
> ---------------------------------------------------------------------
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>
--- End Message ---
--- Begin Message ---
Mimi,
While most everything said is accurate enough, one important factor has
been left out. Your current mileage is better than you think; your
odometer and speedometer are different measurements by the same
instrument. Since your speedometer is under-reporting your speed, your
odometer is also under-reporting your mileage. Some of your "mileage
loss" is not lost and is merely appearing to be lost just because you are
traveling more miles than your odometer records.
If you have an electronic speedometer, like almost all vehicles do these
days like my 2001 Dodge, you can have the speedometer recalibrated for
not much. I had mine done last month for $16 and it just takes a few
minutes. Recalibration helps check your mileage accurately because your
nominal or even measured tire diameter is not the rolling diameter and it
helps avoid speeding tickets.
An example of rolling diameter vs. manufacturer's stated diameter: My
tire diameter is 36.3 inches, but according to my GPS and my
calculations, my rolling diameter is only 34.75 inches (580 revolutions
per mile vs. 555 revolutions per mile). Tires are not steel wheels and
have considerable deformation while driving.
Philip Moss
philipm...@juno.com
____________________________________________________________
Woman is 57 But Looks 27
Mom publishes simple facelift trick that angered doctors...
http://thirdpartyoffers.juno.com/TGL3141/501921e481b2d21e4584dst51vuc
--- End Message ---
--- Begin Message ---
http://www.consumerenergycenter.org/transportation/consumer_tips/speeding_and_mpg.html
********************************************************
Diana R. Tomchick
Professor
Dept. of Biochemistry
University of Texas Southwestern Medical Center
5323 Harry Hines Blvd.
Dallas, TX 75390-8816
(214) 645-6383 (office)
(214) 418-5827 (cell)
diana.tomch...@utsouthwestern.edu
________________________________
UT Southwestern Medical Center
The future of medicine, today.
--- End Message ---
