2009, comeback for low rolling resistance tires ?

[Jeff Shanab]

I was reading a magazine that had a blurb abut the 2009 F-150 truck
which has a "SFE" version fords "super fuel economy" version.
One thing that caught my eye was the use of low rolling resistance tires
and in larger sizes.

"18-inch chrome clad aluminum wheels
<http://www.autospies.com/news/2009-Ford-F150-SFE-34918/#>with low
rolling resistance P265/60R18 all-season tires."
and apparently there is a 20" option too for those bling addicts that
want a heavier rim to totally offset the low rolling resistance.

Not very low profile but a bit of googleing and we see the GM has it's
"XFE" "eXtra fuel economy"  line to match. (sheesh more TLA's)
They have goodyear and conti's in 15" size for the cobalt for example.

The phrases that worry me are "worked with the tire manufacturer to
create a tire especially for the cobalt".; which could mean we can't buy
them.

But here is hoping that low rolling resistance tires will gain enough
momentum to tip the scales and make a comeback.
I want to rolling resistance standards posted on the tire along with the
treadwear and traction ratings :-)

Funny are how many blog entries there are saying "low rolling resistance
= unstable or unsafe in any inclement weather " and none about fair
weather braking differences.

Don't worry, I know lower rolling resistance doesn't automatically mean
less traction.

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[David Roden-3]

On 26 Jun 2009 at 7:22, Jeff Shanab wrote:

> The phrases that worry me are "worked with the tire manufacturer to
> create a tire especially for the cobalt".; which could mean we can't buy
> them.

IIRC, Honda worked with Goodyear to create the Invicta GLR for the Civic HF
models.  These were fairly widely available for many years afterward, and a
popular choice for conversion EVs even though they had some faults.  

I'd guess that if you can learn the correct internal order number, you
should be able to get any LRR tire made for any OEM, as long as it's still
in production.

David Roden - Akron, Ohio, USA
EVDL Administrator

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[Ricky Suiter]

There certainly has been a resurgence in LRR tires in the last two months. I needed a set of new tires for my Saturn conversion and bugged Bridgestone continuously to bring their new Ecopia EP100 tire here, but the answer was only "it's not intended for the US market." Two months after I bought new Michelins they begin selling them. Here's a few of what they are offering specifically for LRR:

Bridgestone Ecopia EP100:
http://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Ecopia+EP100

Ecopia EP20 just showed up recently as an OEM Prius replacement tire:
http://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Ecopia+EP20

Ecopia EP-02 is the Rav4 EV tire that has been around all along:
http://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Ecopia+EP-02

Goodyear Assurance Fuel Max, they've actually been running TV commercials for this tire:
http://www.tirerack.com/tires/tires.jsp?tireMake=Goodyear&tireModel=Assurance+Fuel+Max

Michelin Energy Saver. All their "Energy" line of tires are supposed to be LRR and I have a set of Energy MXV4S8's on my Saturn. I'm happy with it, but they are heavy tires:
http://www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=Energy+Saver+A%2FS

They also make a version of the Hydroedge in LRR:
http://www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=HydroEdge+with+Green+X

If you'd asked about this last year you would have only had a few sparse choices, but now it's definitely a competition.


Regards,
Rick
92 Saturn SC Conversion
AZ Alt Fuel Plates "ZEROGAS"



-------------------------------------------------------
I was reading a magazine that had a blurb abut the 2009 F-150 truck
which has a "SFE" version fords "super fuel economy" version.
One thing that caught my eye was the use of low rolling resistance tires
and in larger sizes.

"18-inch chrome clad aluminum wheels
<http://www.autospies.com/news/2009-Ford-F150-SFE-34918/#>with low
rolling resistance P265/60R18 all-season tires."
and apparently there is a 20" option too for those bling addicts that
want a heavier rim to totally offset the low rolling resistance.

Not very low profile but a bit of googleing and we see the GM has it's
"XFE" "eXtra fuel economy"  line to match. (sheesh more TLA's)
They have goodyear and conti's in 15" size for the cobalt for example.

The phrases that worry me are "worked with the tire manufacturer to
create a tire especially for the cobalt".; which could mean we can't buy
them.

But here is hoping that low rolling resistance tires will gain enough
momentum to tip the scales and make a comeback.
I want to rolling resistance standards posted on the tire along with the
treadwear and traction ratings :-)

Funny are how many blog entries there are saying "low rolling resistance
= unstable or unsafe in any inclement weather " and none about fair
weather braking differences.

Don't worry, I know lower rolling resistance doesn't automatically mean
less traction.




     

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[Darrin-12]

I had a conversation with a friend in the tire industry and he feels that
rolling resistance testing and labeling will happen within the next two
years.  The EPA and NHTSA are teaming to require rolling resistance data be
made public on all tires.  Here's a link to a NHTSA pdf with example labels:

http://www.nhtsa.dot.gov/staticfiles/DOT/NHTSA/Rulemaking/Rules/Associated%20Files/Label_Examples.pdf



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[m gol]

Hey thanks for the links.

Got any ideas where I can get some light weight 14" rims for a Geo Metro?

On Sat, Jun 27, 2009 at 10:06 AM, Ricky Suiter <ricksuiter@...> wrote:

>
> There certainly has been a resurgence in LRR tires in the last two months.
> I needed a set of new tires for my Saturn conversion and bugged Bridgestone
> continuously to bring their new Ecopia EP100 tire here, but the answer was
> only "it's not intended for the US market." Two months after I bought new
> Michelins they begin selling them. Here's a few of what they are offering
> specifically for LRR:
>
> Bridgestone Ecopia EP100:
>
> http://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Ecopia+EP100
>
> Ecopia EP20 just showed up recently as an OEM Prius replacement tire:
>
> http://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Ecopia+EP20
>
> Ecopia EP-02 is the Rav4 EV tire that has been around all along:
>
> http://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Ecopia+EP-02
>
> Goodyear Assurance Fuel Max, they've actually been running TV commercials
> for this tire:
>
> http://www.tirerack.com/tires/tires.jsp?tireMake=Goodyear&tireModel=Assurance+Fuel+Max
>
> Michelin Energy Saver. All their "Energy" line of tires are supposed to be
> LRR and I have a set of Energy MXV4S8's on my Saturn. I'm happy with it, but
> they are heavy tires:
>
> http://www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=Energy+Saver+A%2FS
>
> They also make a version of the Hydroedge in LRR:
>
> http://www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=HydroEdge+with+Green+X
>
> If you'd asked about this last year you would have only had a few sparse
> choices, but now it's definitely a competition.
>
>
> Regards,
> Rick
> 92 Saturn SC Conversion
> AZ Alt Fuel Plates "ZEROGAS"
>
>
>
> -------------------------------------------------------
> I was reading a magazine that had a blurb abut the 2009 F-150 truck
> which has a "SFE" version fords "super fuel economy" version.
> One thing that caught my eye was the use of low rolling resistance tires
> and in larger sizes.
>
> "18-inch chrome clad aluminum wheels
> <http://www.autospies.com/news/2009-Ford-F150-SFE-34918/#>with low
> rolling resistance P265/60R18 all-season tires."
> and apparently there is a 20" option too for those bling addicts that
> want a heavier rim to totally offset the low rolling resistance.
>
> Not very low profile but a bit of googleing and we see the GM has it's
> "XFE" "eXtra fuel economy"  line to match. (sheesh more TLA's)
> They have goodyear and conti's in 15" size for the cobalt for example.
>
> The phrases that worry me are "worked with the tire manufacturer to
> create a tire especially for the cobalt".; which could mean we can't buy
> them.
>
> But here is hoping that low rolling resistance tires will gain enough
> momentum to tip the scales and make a comeback.
> I want to rolling resistance standards posted on the tire along with the
> treadwear and traction ratings :-)
>
> Funny are how many blog entries there are saying "low rolling resistance
> = unstable or unsafe in any inclement weather " and none about fair
> weather braking differences.
>
> Don't worry, I know lower rolling resistance doesn't automatically mean
> less traction.
>
>
>
>
>
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
>

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[Phil Marino-2]

I wouldn't worry too much about rim weight.  It might be easier ( and
cheaper) to save weight elsewhere.  The difference between stock steel rims
and expensive aluminum rims is not generally very much.  And, the "rolling
inertia" effect of rims is fairly small ( despite common thinking on this).
Phil Marino
Rochester, NY

On Thu, Jul 2, 2009 at 4:18 AM, m gol <gol.m86@...> wrote:

> Hey thanks for the links.
>
> Got any ideas where I can get some light weight 14" rims for a Geo Metro?
>
> On Sat, Jun 27, 2009 at 10:06 AM, Ricky Suiter <ricksuiter@...>
> wrote:
>
> >
> > There certainly has been a resurgence in LRR tires in the last two
> months.
> > I needed a set of new tires for my Saturn conversion and bugged
> Bridgestone
> > continuously to bring their new Ecopia EP100 tire here, but the answer
> was
> > only "it's not intended for the US market." Two months after I bought new
> > Michelins they begin selling them. Here's a few of what they are offering
> > specifically for LRR:
> >
> > Bridgestone Ecopia EP100:
> >
> >
> http://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Ecopia+EP100
> >
> > Ecopia EP20 just showed up recently as an OEM Prius replacement tire:
> >
> >
> http://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Ecopia+EP20
> >
> > Ecopia EP-02 is the Rav4 EV tire that has been around all along:
> >
> >
> http://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Ecopia+EP-02
> >
> > Goodyear Assurance Fuel Max, they've actually been running TV commercials
> > for this tire:
> >
> >
> http://www.tirerack.com/tires/tires.jsp?tireMake=Goodyear&tireModel=Assurance+Fuel+Max
> >
> > Michelin Energy Saver. All their "Energy" line of tires are supposed to
> be
> > LRR and I have a set of Energy MXV4S8's on my Saturn. I'm happy with it,
> but
> > they are heavy tires:
> >
> >
> http://www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=Energy+Saver+A%2FS
> >
> > They also make a version of the Hydroedge in LRR:
> >
> >
> http://www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=HydroEdge+with+Green+X
> >
> > If you'd asked about this last year you would have only had a few sparse
> > choices, but now it's definitely a competition.
> >
> >
> > Regards,
> > Rick
> > 92 Saturn SC Conversion
> > AZ Alt Fuel Plates "ZEROGAS"
> >
> >
> >
> > -------------------------------------------------------
> > I was reading a magazine that had a blurb abut the 2009 F-150 truck
> > which has a "SFE" version fords "super fuel economy" version.
> > One thing that caught my eye was the use of low rolling resistance tires
> > and in larger sizes.
> >
> > "18-inch chrome clad aluminum wheels
> > <http://www.autospies.com/news/2009-Ford-F150-SFE-34918/#>with low
> > rolling resistance P265/60R18 all-season tires."
> > and apparently there is a 20" option too for those bling addicts that
> > want a heavier rim to totally offset the low rolling resistance.
> >
> > Not very low profile but a bit of googleing and we see the GM has it's
> > "XFE" "eXtra fuel economy"  line to match. (sheesh more TLA's)
> > They have goodyear and conti's in 15" size for the cobalt for example.
> >
> > The phrases that worry me are "worked with the tire manufacturer to
> > create a tire especially for the cobalt".; which could mean we can't buy
> > them.
> >
> > But here is hoping that low rolling resistance tires will gain enough
> > momentum to tip the scales and make a comeback.
> > I want to rolling resistance standards posted on the tire along with the
> > treadwear and traction ratings :-)
> >
> > Funny are how many blog entries there are saying "low rolling resistance
> > = unstable or unsafe in any inclement weather " and none about fair
> > weather braking differences.
> >
> > Don't worry, I know lower rolling resistance doesn't automatically mean
> > less traction.
> >
> >
> >
> >
> >
> >
> > _______________________________________________
> > General EVDL support: http://evdl.org/help/
> > Usage guidelines: http://evdl.org/help/index.html#conv
> > Archives: http://evdl.org/archive/
> > Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
> >
> >
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[Roland Wiench]

Hey thanks for the links.

Got any ideas where I can get some light weight 14" rims for a Geo Metro?


You have to match the load rating of the wheel to the load rating of the
tire.  Plus thrust force that the wheel is subjected to while acceleration
and braking which is calculated by the total weight of the vehicle divided
by two which may be apply to one drive wheel.

In a very light weight 16 inch rim, my specifications for the wheel came to
the actual weight on that wheel plus another 20 percent for static load
which came to 2600 lbs rating.  The thrust rating of 200 percent of the
actual weight on that wheel which came to 4000 lbs.

These had to be custom made by CenterLine.Com which makes racing type wheels
by spinning a aluminum sheet into a wheel.  They are not cast.  I would had
to order 100 wheels to get the price down to $500.00 each back in the 80's.
Just to tool up for one set would cost about $10,000.00.

The wheel I had to choose, has 5/16 inch thick center plate that is full
welded to the rim which has a thrust rating of 4000 lbs.

You also have to match your axle and bearing set to the thrust rating.

When my EV was built back in 1977, it only use the standard set of bearings
and axils.  They only lasted a year, where the bearings grind a groove
through the spinals and axles surfaces.

Roland

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[Ricky Suiter]

On Tirerack look up Kosei brand wheels. They're the most reasonably priced light weight wheels I've found. I have a set of 15" K1-TS wheels on my Saturn and I'm relatively happy with them. The 14's weight in at 9.3lbs. The K3 model is also available in a 14 at 10.6 lbs and they're on closeout right now for only $89 each.

I did have to recently replace one of my wheels though. I had a tire I figured had a nail in it and was slowly leaking. When it took it to the tire store they put it under water and immediately had me come back out in to the shop to show me something. The wheel itself was leaking air right where one of the spokes goes to the outer wheel surface. I had never curbed the wheel, but maybe I hit a pothole too hard or something. There is a visible fissure in the metal at the bead. The wheel was almost 3 years old when this happened so I guess I got my use out of it. The wheel is stamped inside as rated for 500kg. I don't have that much weight on it.

I went a little nuts and bought a set of the 14's for my Ford Th!nk Neighbor, haven't had any problems with those.

About the only other option for light weight wheels are Volk which are also known as Rays wheels. Such a size would probably be special order from Japan with at least a 2 month lead time. These wheels would likely be $400-$500 each too! It's something to look at and drool though.

Regards,
Rick
92 Saturn SC Conversion
AZ Alt Fuel Plates "ZEROGAS"

--------------------
>Hey thanks for the links.
>
>Got any ideas where I can get some light weight 14" rims for a Geo Metro?



     

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[m gol]

Doesn't look like Kosei fits the Geo Metro.

Tirerack had two 14" wheels available. They weigh 15 lbs...I was hoping to
get something lighter for the same price...like you did...

On Thu, Jul 2, 2009 at 9:09 AM, Ricky Suiter <ricksuiter@...> wrote:

>
> On Tirerack look up Kosei brand wheels. They're the most reasonably priced
> light weight wheels I've found. I have a set of 15" K1-TS wheels on my
> Saturn and I'm relatively happy with them. The 14's weight in at 9.3lbs. The
> K3 model is also available in a 14 at 10.6 lbs and they're on closeout right
> now for only $89 each.
>
> I did have to recently replace one of my wheels though. I had a tire I
> figured had a nail in it and was slowly leaking. When it took it to the tire
> store they put it under water and immediately had me come back out in to the
> shop to show me something. The wheel itself was leaking air right where one
> of the spokes goes to the outer wheel surface. I had never curbed the wheel,
> but maybe I hit a pothole too hard or something. There is a visible fissure
> in the metal at the bead. The wheel was almost 3 years old when this
> happened so I guess I got my use out of it. The wheel is stamped inside as
> rated for 500kg. I don't have that much weight on it.
>
> I went a little nuts and bought a set of the 14's for my Ford Th!nk
> Neighbor, haven't had any problems with those.
>
> About the only other option for light weight wheels are Volk which are also
> known as Rays wheels. Such a size would probably be special order from Japan
> with at least a 2 month lead time. These wheels would likely be $400-$500
> each too! It's something to look at and drool though.
>
> Regards,
> Rick
> 92 Saturn SC Conversion
> AZ Alt Fuel Plates "ZEROGAS"
>
> --------------------
> >Hey thanks for the links.
> >
> >Got any ideas where I can get some light weight 14" rims for a Geo Metro?
>
>
>
>
>
> _______________________________________________
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[Ricky Suiter]

What is the bolt pattern and offset? The 14's I got are 4X100mm and 38mm offset, which is very common. I'm guessing not that many people are looking for wheels for a Geo Metro so it might be worth giving them a call on the phone.

Ohh, and Discount Tire will price match Tire Rack.

Rick

---------------------------
>Doesn't look like Kosei fits the Geo Metro.
>
>Tirerack had two 14" wheels available. They weigh 15 lbs...I was hoping to
>get something lighter for the same price...like you did...



     

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[m gol]

The tirerack does have two rims for the Geo:
Offset: +38mm or 44mm
Backspacing: 5.00" or 5.04"
Bolt Pattern: 4-114

I guess they are OK, but they are 15 pounds, which gets me jealous that you
got 10 pound ones...

On Thu, Jul 2, 2009 at 1:53 PM, Ricky Suiter <ricksuiter@...> wrote:

>
> What is the bolt pattern and offset? The 14's I got are 4X100mm and 38mm
> offset, which is very common. I'm guessing not that many people are looking
> for wheels for a Geo Metro so it might be worth giving them a call on the
> phone.
>
> Ohh, and Discount Tire will price match Tire Rack.
>
> Rick
>
> ---------------------------
> >Doesn't look like Kosei fits the Geo Metro.
> >
> >Tirerack had two 14" wheels available. They weigh 15 lbs...I was hoping to
> >get something lighter for the same price...like you did...
>
>
>
>
>
> _______________________________________________
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[Jeff Shanab]

>
> I wouldn't worry too much about rim weight.  It might be easier ( and
> cheaper) to save weight elsewhere.  The difference between stock steel rims
> and expensive aluminum rims is not generally very much.  And, the "rolling
> inertia" effect of rims is fairly small ( despite common thinking on this).
> Phil Marino
> Rochester, NY

I am gonna disagree or clarify slightly. but maybe it is a left coast
thing.

The extra energy used to spin up the additional mass also reduces
braking capacity and chews up brakes faster.

The stock steel rims are often not as bad as people think especially for
the stock tire size or when compared to the oversize billet aluminum
rims that people go nuts for out here.  Although they sell for high
dollar they are actually low cost in the world of rims, cast with all
concentration on looks not strength or weight.

People out here go stupid. The shinier and bigger is better syndrome.
Ever seen a honda civic with 22" rims?

That said, luckily there is a good way to measure it. :-)

Here is how it really works out.
  The rim + tire weight (bigger rim means more tire weight, even if low
profile) is totally unsprung weight.
   As a vehicle comes to a bump, the wheel is launched up into the air.
This is reacted against by the spring which is constrained by the body
of the car.  The spring pushes the tire back down to the road and the
shock slows this return to reduce the reaction so it doesn't overshoot.
We turn it into an over-dampened oscillation with a short period.

  If you have a small light vehicle you only have so much weigh to
resist against the spring and the flying unsprung weight. To much
unsprung weight and the tire won't be held in contact with the road on a
bumpy surface for enough percent of the time. It becomes like a stone
skipping across a pond. I have witnessed this on these stupid people
putting huge shiny rims on those hondas, they hit a dip in the road at
an intersection and they are all over the road.  And have experienced it
on my autocrossing.

  At least in an EV we are usually increasing the weight, we therefore
can tolerate a higher weight rim. At least from the handling
perspective.  A  larger diameter usually gives a better ride, so
something like the Prius has to be very careful to keep the overall
unsprung weight down, but also at a know number to maintain a good ride.
The lighter the tighter the tolerance.

  For rotational inertia, and how it effects acceleration, they say a lb
of rotating mass is equal to about 4 lbs of weight.
  I can vouch for that. Repeated testing.
 
  Often the choice to go away from a stock rim, is to get a different
tire size, the steel stamped rims are usually for a narrow tire, that is
where they are most economical.  As a rim gets wider steels flexibility
starts to require thicker sections which increases weight. You quickly
pass a point where the rigidity of aluminum helps more than it's reduced
strength. It is also cheaper to cast deep than it is to stamp deep. As I
typed this I was trying to think of even one "sports car" that doesn't
have alloy rims, at  least 80's on.

In my driveway sites an 88 mitsu PU It came with stamped steel rims but
became my autocross vehicle (long story) and it has a set of cyclone-2s
on it. These are the 70's era mags, very rigid and light.
The 95 grand am came stock with aluminum rims
The 87 300zx(EV) came stock with aluminum rims.

Get out the scale. If you are shopping rims and ask the guy how much a
rim weighs and he can't answer,  shop somewhere else, this guy is
selling rims on look and they are probably 3x what they need and ride
and handling and braking will suffer!
 
 

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[Phil Marino-2]

On Fri, Jul 3, 2009 at 10:40 AM, Jeff Shanab <jshanab@...> wrote:

> >
> > I wouldn't worry too much about rim weight.  It might be easier ( and
> > cheaper) to save weight elsewhere.  The difference between stock steel
> rims
> > and expensive aluminum rims is not generally very much.  And, the
> "rolling
> > inertia" effect of rims is fairly small ( despite common thinking on
> this).
> > Phil Marino
> > Rochester, NY
>
> I am gonna disagree or clarify slightly. but maybe it is a left coast
> thing.
>
> The extra energy used to spin up the additional mass also reduces
> braking capacity and chews up brakes faster.
>
>
> That said, luckily there is a good way to measure it. :-)
>
>
>  For rotational inertia, and how it effects acceleration, they say a lb
> of rotating mass is equal to about 4 lbs of weight.
>  I can vouch for that. Repeated testing.
>

 Jeff


For tires and wheels, the equivalent extra mass (due to rotation) is ALWAYS
less than the static (actual) weight.  One way to think about it:  if  all
the weight was on the outer edge of the tire, the energy due to its
rotational inertia would be exactly equal to it's straight-line energy (
because its rotational speed would equal its straight-line speed.)  In that
case the extra "mass" due to rotation would be equal to the real mass.  AND,
adding one pound of tire weight would be like adding two pounds of driver
weight. ( Even this is only for acceleration and braking, this extra pound
does not add any hill-climbing drag, or any rolling resistance drag, like
the extra pound on the driver does)


To find out the real numbers, a couple of years ago, I took a wheel and tire
from my car (B381 185/65 -14 tire and stock 14 inch Toyota Echo rim) and
measured the rotational inertia of each one. i used a bifilar pendulum -
essentially hang it from three ropes, spin it, and measure the oscillation
frequency.

The tire weighed 16.0 pounds, the inertia was 1712 lb-in^2, and the
additional effective mass (due to rotation) was 11.38#. So, the rotational
mass factor was 0.83. So, as far as acceleration the tire acted like 16 +
11.38 lbs = 27.38#.

For the rim, the actual weight was 12.7 lbs, and the equivalent rotational
weight was 3.8 #.(factor or 0.3), so the rim acted like 12.7 + 3.8 = 16 lbs
as far as acceleration is concerned

As you'd expect the tire rotational effects are greater because more of the
mass is at a larger radius.


SO, For rotational inertia, and how it effects acceleration:

1 lb of rotating mass ( tire weight) is rotationally equal to about 0.83 lbs
of weight ( or, 1.83 total) and 1 lb of rim weight is equivalent to 1.3 #
total.

This is real, measured data - for these particular parts.
 Obviously you would get slightly different results based on the
particular tire and the particular rim.


So, it's not such a big deal, unless you're drag racing, and every 0.01 s
counts.

If anyone is really interested, I can post a picture of the test and a
spread sheet of the calculations I made to get these results.  Let me know.

Phil Marino
Rochester, NY

>
>
>
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