From: Jeff Strickland on

"Hachiroku ????" <Trueno(a)e86.GTS> wrote in message
news:pan.2009.09.03.18.55.37.548677(a)e86.GTS...
> On Thu, 03 Sep 2009 08:57:26 -0700, Jeff Strickland wrote:
>
>>
>> The wider tire, by itself would not change the speedo. But the aspect
>> ratio
>> (sidewall height) is a percentage of the width, so the wider tire will
>> give
>> a taller tire if the aspect RATIO remains the same. 45% of 225 is a
>> bigger
>> number than 45% of 215, so the 225 is not only wider, it's taller as
>> well.
>
> Back when I was sitting in the Used Car Sales office, and had not much to
> do between customers, I came up with a spreadsheet that would calculate
> the speedo error based on the size tire, and give you the actual MPH based
> on tire size. I did it by coming up with the circumference of the tire,
> and then formulating that into 5,280 feet per mile. It was pretty slick I
> posted it here about 5-6 years ago.
>
>
>

How do you calculate the ERROR based on tire size? The best I can figure out
is the variance in the error when the tire size changes.

The auto maker wants the speedo to read 45 when you are doing 43, or 70 when
doing 66, so that you can't claim that it said 40 when you got a ticket for
doing 50 in a 45. But, how can you calculate any amount of error knowing
only the tire size. The best you can do is determine the plus/minus change
in the speedo when a custom tire is fitted.







From: nm5k on
On Sep 2, 6:25 pm, Hachiroku ハチロク <Tru...(a)e86.GTS> wrote:
> On Sun, 30 Aug 2009 21:44:52 -0700, PHATRS wrote:
>
> > I did 298 km/h in my RenaultSport Megane 225 the other day down Toorak
> > Rd.
>
> Hmmm...
>
> Speedo in my Scion tC said 122 (MPH), but GPS only registered 116.
> Which do I believe?
>
> Would have tried to go a little more, but was coming up on an 18 wheeler
> and a blind hill. I-91 in VT, 2 year old pavement. Nice and smooth.
>
> Must be getting cowardly in my 'old age'. I took the Hachi up to 131, then
> to 125 for ~25 minutes, but only hit 122 for about 2 minutes.
>
> Maybe another run next time...see what top speed is...

Take a little walk on the wild side..
Look at those stripes flip by...
Outrunning a few of the smaller aircraft in common use
these days. :)
One of my fav cars. Period..
http://www.youtube.com/watch?v=3VXM-wKsZnQ
http://www.youtube.com/watch?v=eVLac7JGSgw&feature=related

Gives crotch rocket a whole new meaning..
If you blew a tire, they would probably have to scrape you off
the highway with a snow shovel.. :/
That takes some serious nads to do 200+ on a motorcycle..
http://www.youtube.com/watch?v=tcYxr0RsIlY&feature=related
http://www.youtube.com/watch?v=5-LAQY5ESc4&feature=related
From: Hachiroku on
On Fri, 04 Sep 2009 18:26:00 -0700, Jeff Strickland wrote:

>
> "Hachiroku ????" <Trueno(a)e86.GTS> wrote in message
> news:pan.2009.09.03.18.55.37.548677(a)e86.GTS...
>> On Thu, 03 Sep 2009 08:57:26 -0700, Jeff Strickland wrote:
>>
>>>
>>> The wider tire, by itself would not change the speedo. But the aspect
>>> ratio
>>> (sidewall height) is a percentage of the width, so the wider tire will
>>> give
>>> a taller tire if the aspect RATIO remains the same. 45% of 225 is a
>>> bigger
>>> number than 45% of 215, so the 225 is not only wider, it's taller as
>>> well.
>>
>> Back when I was sitting in the Used Car Sales office, and had not much to
>> do between customers, I came up with a spreadsheet that would calculate
>> the speedo error based on the size tire, and give you the actual MPH based
>> on tire size. I did it by coming up with the circumference of the tire,
>> and then formulating that into 5,280 feet per mile. It was pretty slick I
>> posted it here about 5-6 years ago.
>>
>>
>>
>
> How do you calculate the ERROR based on tire size? The best I can figure out
> is the variance in the error when the tire size changes.
>
> The auto maker wants the speedo to read 45 when you are doing 43, or 70 when
> doing 66, so that you can't claim that it said 40 when you got a ticket for
> doing 50 in a 45. But, how can you calculate any amount of error knowing
> only the tire size. The best you can do is determine the plus/minus change
> in the speedo when a custom tire is fitted.

Interesting as it may seem, by 'measuring' the speed using those radar
speed readouts the cops set up, the Toyotas I have had with mechanical
speedos were more accurate. They were usually spot on, or within a small
percentage.

For instance, I found out my Tercel was more accurate with 175/70-13s than
with the spec'd 155/80-13s.

The spec'd tire had a diameter of 14.93", while my 'special' tire was
15.64".

The tires I put on were accurate at 70MPH. Don't ask me how I know, we
don't want Joe to start up all over again...



From: nm5k on
On Sep 4, 9:42 pm, Hachiroku ハチロク <Tru...(a)e86.GTS> wrote:
> On Fri, 04 Sep 2009 18:26:00 -0700, Jeff Strickland wrote:
>
> > "Hachiroku ????" <Tru...(a)e86.GTS> wrote in message
> >news:pan.2009.09.03.18.55.37.548677(a)e86.GTS...
> >> On Thu, 03 Sep 2009 08:57:26 -0700, Jeff Strickland wrote:
>
> >>> The wider tire, by itself would not change the speedo. But the aspect
> >>> ratio
> >>> (sidewall height) is a percentage of the width, so the wider tire will
> >>> give
> >>> a taller tire if the aspect RATIO remains the same. 45% of 225 is a
> >>> bigger
> >>> number than 45% of 215, so the 225 is not only wider, it's taller as
> >>> well.
>
> >> Back when I was sitting in the Used Car Sales office, and had not much to
> >> do between customers, I came up with a spreadsheet that would calculate
> >> the speedo error based on the size tire, and give you the actual MPH based
> >> on tire size. I did it by coming up with the circumference of the tire,
> >> and then formulating that into 5,280 feet per mile. It was pretty slick I
> >> posted it here about 5-6 years ago.
>
> > How do you calculate the ERROR based on tire size? The best I can figure out
> > is the variance in the error when the tire size changes.
>
> > The auto maker wants the speedo to read 45 when you are doing 43, or 70 when
> > doing 66, so that you can't claim that it said 40 when you got a ticket for
> > doing 50 in a 45. But, how can you calculate any amount of error knowing
> > only the tire size. The best you can do is determine the plus/minus change
> > in the speedo when a custom tire is fitted.
>
> Interesting as it may seem, by 'measuring' the speed using those radar
> speed readouts the cops set up, the Toyotas I have had with mechanical
> speedos were more accurate. They were usually spot on, or within a small
> percentage.
>
> For instance, I found out my Tercel was more accurate with 175/70-13s than
> with the spec'd 155/80-13s.
>
> The spec'd tire had a diameter of 14.93", while my 'special' tire was
> 15.64".
>
> The tires I put on were accurate at 70MPH. Don't ask me how I know, we
> don't want Joe to start up all over again...

My Corolla is pretty close with new tires. It's almost right on the
money at 70 mph. At the slower speeds, it usually reads a couple
more than what you are doing. IE: you can read 37 and be doing 35.
On mine, the error seems to decrease the faster you go.
Right now, my tires are getting pretty thin, and it's reading 1-2
mph faster than actual even at 70. The error has slightly increased
over the past couple of years. I suspect when I get new skins,
the speedo will be closer and almost right on the money at highway
speeds.
In my case, Joe had nothing to do with my measurements. I had a
GPS before I ever bought that car. So I've GPS tested it since day
one, with at least my Meridian handheld unit. Course, I now have
a tom tom mounted in the thing. The speedo in my old 68 F-250
is so whacked out, I use a GPS as the speedometer, not the one
in the truck. It needs a new gear in the tranny. Slips.. It reads
about 40 mph when you are doing 60.. :/
The corolla normally uses a 185/65-15. I'm pulling my hair out
trying to decide what tires to get. I've still got a while to decide
before they are totally shot, but they are already dangerous in
heavy rain puddles. Fine as long as it's dry..
I keep pondering the "low rolling resistance" tires, as the main
reason I'm driving a puddle jumper like the Corolla is to get
good mpg. Being as the current Goodyear Integrity tires are
fairly low rolling resistance, I'm kind of worried about buying a
cheaper tire that might have a 15-20 % higher rolling resistance.
A 20% decrease in resistance seems to pan out to about a
4% increase in mileage. Which in my car at 40 mpg, would be
say 1.5-2 extra mpg. I did the math, and the extra cost of the
tire would pay for itself eventually vs the cheaper tires.

Many people hate the Integrity.. :( Myself, I don't think it's
that bad, but it does suck in heavy rain when the tread starts
getting thin. But I've got 52k miles on the original OEM set,
so can't complain much about that. I read some reviews where
some complain they wear them out in 20k or so, but they
must drive like speed racer.
I'm kind of leaning to the Goodyear Assurance Fuel Max tire.
Seem to be getting pretty good reviews.
http://www.discounttire.com/dtcs/findTireDetail.do?c=1&rcz=77096&ar=65&rf=true&rd=15&rc=TSWINT&cs=185&dVeh=dVeh&tc=GDYPT7&yr=2005&pc=30348&cf=false&vid=007410&sw=false
They are listing those tires for about $8 less than the Integrity
which
is about $95 a tire. And they get better reviews than the Integrity.


From: Michael on
On Sep 4, 5:34 pm, Hachiroku ハチロク <Tru...(a)e86.GTS> wrote:
> On Fri, 04 Sep 2009 13:40:49 -0400, JoeSpareBedroom wrote:
> > "Jeff Strickland" <crwlrj...(a)yahoo.com> wrote in message
> >news:h7rhso$qlu$1(a)news.eternal-september.org...
>
> >> "JoeSpareBedroom" <newstr...(a)frontiernet.net> wrote in message
> >>news:DSbom.170494$Qg6.128336(a)newsfe14.iad...
>
> >>> What about moving objects other than cars?
>
> >> ???
>
> > Can't think of any such objects?
>
> Moose. Deer. Maybe a bear. We are talking Vermont here.
>
> However, when I was 29 in Canada and took my Hachi up to 130, it was a
> holiday weekend. But there were two other cars a bit in front of me,
> clearing the path.
>
> No balls.


You're in Vermont?

How much is the maple syrup out there?

Maple syrup was about $28 for 1/2 quart (eh, 1/2 liter) at Costco a
few months back. On our trip to Toronto, I was excited to buy it for
CAN$15 per liter. Wow. Then I come home to Sacramento and notice the
price is now $13 per quart.

Michael