I think the larger tire gets slightly better highway mileage because it
rolls farther per revolution, but this is directly offset by the extra
air drag of being higher up into the flow with more of the undercarriage
exposed.

In other words, I think I get exactly the same mileage with 31's as I
now get with 33's taking the difference in odometer readings in account.

I have a regular 200 mile run that I get to check gas brands and octanes
out on. Different brands of 'fuel' make up to 10 mpg difference in my
CJ7!

My speedometer and odometer are exact with 33's on her according to many
GPS checks.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Ken Knapp wrote:
>
> You know, one thing I've been curious about is how the tire size will relate
> to mpg - taller tires give you higher or lower mpg. I can argue it either
> way in my head.
>
> Ken

 

That part could be consider an overdrive, and may help in mileage,
unless the RPM dropped below it's efficient range. It's the weight, same
reason Hot Rodders want a light aluminum flywheel.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

Lee Ayrton wrote:
>
> Isn't there a leverage problem involved, too? You're asking the device to
> move a slightly heavier weight at the end of a longer lever (the radius
> from hub to ground).

 

That part could be consider an overdrive, and may help in mileage,
unless the RPM dropped below it's efficient range. It's the weight, same
reason Hot Rodders want a light aluminum flywheel.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

Lee Ayrton wrote:
>
> Isn't there a leverage problem involved, too? You're asking the device to
> move a slightly heavier weight at the end of a longer lever (the radius
> from hub to ground).

 

That part could be consider an overdrive, and may help in mileage,
unless the RPM dropped below it's efficient range. It's the weight, same
reason Hot Rodders want a light aluminum flywheel.
God Bless America, ßill O|||||||O
mailto:-------------------- http://www.----------.com/

Lee Ayrton wrote:
>
> Isn't there a leverage problem involved, too? You're asking the device to
> move a slightly heavier weight at the end of a longer lever (the radius
> from hub to ground).

 

Heh. Big tires as overdrive. Hadn't even thought of that, thanks.


On Thu, 3 Feb 2005, L.W.([iso-8859-1] ßill) ------ III wrote:

> That part could be consider an overdrive, and may help in mileage,
> unless the RPM dropped below it's efficient range. It's the weight, same
> reason Hot Rodders want a light aluminum flywheel.
> God Bless America, ßill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Lee Ayrton wrote:
>>
>> Isn't there a leverage problem involved, too? You're asking the device to
>> move a slightly heavier weight at the end of a longer lever (the radius
>> from hub to ground).
>

--
"I defer to your plainly more vivid memories of topless women with
whips....r"
R. H. Draney recalls AFU in the Good Old Days.

 

Heh. Big tires as overdrive. Hadn't even thought of that, thanks.


On Thu, 3 Feb 2005, L.W.([iso-8859-1] ßill) ------ III wrote:

> That part could be consider an overdrive, and may help in mileage,
> unless the RPM dropped below it's efficient range. It's the weight, same
> reason Hot Rodders want a light aluminum flywheel.
> God Bless America, ßill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Lee Ayrton wrote:
>>
>> Isn't there a leverage problem involved, too? You're asking the device to
>> move a slightly heavier weight at the end of a longer lever (the radius
>> from hub to ground).
>

--
"I defer to your plainly more vivid memories of topless women with
whips....r"
R. H. Draney recalls AFU in the Good Old Days.

 

Heh. Big tires as overdrive. Hadn't even thought of that, thanks.


On Thu, 3 Feb 2005, L.W.([iso-8859-1] ßill) ------ III wrote:

> That part could be consider an overdrive, and may help in mileage,
> unless the RPM dropped below it's efficient range. It's the weight, same
> reason Hot Rodders want a light aluminum flywheel.
> God Bless America, ßill O|||||||O
> mailto:-------------------- http://www.----------.com/
>
> Lee Ayrton wrote:
>>
>> Isn't there a leverage problem involved, too? You're asking the device to
>> move a slightly heavier weight at the end of a longer lever (the radius
>> from hub to ground).
>

--
"I defer to your plainly more vivid memories of topless women with
whips....r"
R. H. Draney recalls AFU in the Good Old Days.

 

Well, it takes more engine torque to get those big meats turning....but that
just might put your RPM's in the advanced range, so it would make much
difference!

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:420236F2.BA91EE3C@sympatico.ca...
>I think the larger tire gets slightly better highway mileage because it
> rolls farther per revolution, but this is directly offset by the extra
> air drag of being higher up into the flow with more of the undercarriage
> exposed.
>
> In other words, I think I get exactly the same mileage with 31's as I
> now get with 33's taking the difference in odometer readings in account.
>
> I have a regular 200 mile run that I get to check gas brands and octanes
> out on. Different brands of 'fuel' make up to 10 mpg difference in my
> CJ7!
>
> My speedometer and odometer are exact with 33's on her according to many
> GPS checks.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Ken Knapp wrote:
>>
>> You know, one thing I've been curious about is how the tire size will
>> relate
>> to mpg - taller tires give you higher or lower mpg. I can argue it either
>> way in my head.
>>
>> Ken

 

Well, it takes more engine torque to get those big meats turning....but that
just might put your RPM's in the advanced range, so it would make much
difference!

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:420236F2.BA91EE3C@sympatico.ca...
>I think the larger tire gets slightly better highway mileage because it
> rolls farther per revolution, but this is directly offset by the extra
> air drag of being higher up into the flow with more of the undercarriage
> exposed.
>
> In other words, I think I get exactly the same mileage with 31's as I
> now get with 33's taking the difference in odometer readings in account.
>
> I have a regular 200 mile run that I get to check gas brands and octanes
> out on. Different brands of 'fuel' make up to 10 mpg difference in my
> CJ7!
>
> My speedometer and odometer are exact with 33's on her according to many
> GPS checks.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Ken Knapp wrote:
>>
>> You know, one thing I've been curious about is how the tire size will
>> relate
>> to mpg - taller tires give you higher or lower mpg. I can argue it either
>> way in my head.
>>
>> Ken

 

Well, it takes more engine torque to get those big meats turning....but that
just might put your RPM's in the advanced range, so it would make much
difference!

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:420236F2.BA91EE3C@sympatico.ca...
>I think the larger tire gets slightly better highway mileage because it
> rolls farther per revolution, but this is directly offset by the extra
> air drag of being higher up into the flow with more of the undercarriage
> exposed.
>
> In other words, I think I get exactly the same mileage with 31's as I
> now get with 33's taking the difference in odometer readings in account.
>
> I have a regular 200 mile run that I get to check gas brands and octanes
> out on. Different brands of 'fuel' make up to 10 mpg difference in my
> CJ7!
>
> My speedometer and odometer are exact with 33's on her according to many
> GPS checks.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Ken Knapp wrote:
>>
>> You know, one thing I've been curious about is how the tire size will
>> relate
>> to mpg - taller tires give you higher or lower mpg. I can argue it either
>> way in my head.
>>
>> Ken