Date: Thu, 4 Jan 2018 18:06:49 +0000
Reply-To: Keith Hughes <keithahughes@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Keith Hughes <keithahughes@YAHOO.COM>
Subject: Re: vanagon Digest - 3 Jan 2018 to 4 Jan 2018 - Special issue
(#2018-7)
Content-Type: text/plain; charset=UTF-8
I think what Dennis is saying is that the relationship between the tach and the speedo don't change with tire size. That is strictly a function of gear ratios. If the engine spins the tire one revolution per 4 engine revolutions, that doesn't change with tire size. Only the actual distance traveled changes.
Keith Hughes
'86 Westy GenV (Marvin)
------------------------------
Date: Thu, 4 Jan 2018
08:50:00 -0800
From: David McNeely <davmcneely40@GMAIL.COM>
Subject: Re: Locking differential
Dennis, I believe that an increase in
tire diameter, which is also an
increase in tire perimeter, does alter
the speedometer and the tachometer,
slightly or more depending on how large
the increase is. What the cable
counts is rotations. A larger
tire means fewer rotations per mile,
therefore both the tach and the
speedometer register lower than with the
factory set up. In another
vehicle, I have been stopped for speeding when
I had oversized tires. The
officer and I had a discussion about that, and
he let me off with a warning due to
that fact. And it is a fact, unless my
mathematics education was wrong.
If this is wrong, please advise me how it
is wrong.
This does not alter your reasoning
regarding the tire the original poster
is running, or the other sizes you
mention, because of the nominal increase
over factory size.
On Wed, Jan 3, 2018 at 7:51 PM, Dennis
Haynes <d23haynes57@hotmail.com>
wrote:
> A 205/70-15 tire is ~26.3"
diameter which is a very mild increase over th=
e
> original size of 25.6". This is
about 795 revs/mile. The reading between
> the tachometer and speedometer
does not change with tire size, only how f=
ar
> or fast the vehicle actuals
travels does. A lot of folks go with 215/60-=
16
> or 215/55-17 as they are also this
diameter. I like to 225/60-16 or
> 225/55-17 to get bit more diameter
and width along with increased weight
> ratings. Syncros 235/55-17 is
becoming a favorite. So, at 30 mph in town
> speed what is the problem with 3rd
gear and 2,400 rpm? Sounds like a swee=
t
> spot. 3rd gear is almost 1 to 1
leaving the final drive as the real gear
> reduction from engine to axles.
4th is an overdrive, the output spins
> faster than the engine which
further reduces torque, leverage in wrong
> direction. I think you probably
have a good reasonable setup with the 2.2=
.
>
> Dennis
>
>
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