Re: Gear Ratios

[Tom Mandera <tsm1@domain.elided>]

On Wed, 7 Jan 1998, Scott Machalk wrote:

> I finally got around to checking out my speedometer the other day and I
> found out that when it reads 50 I'm actually going 44 mph. 
> 
> This is not what I expected. I figured that since I'm running 32" tires
> that the speedometer would be reading low. On the other hand, if the gears
> were changed, this would account for the unexpected results.
> 
> Am I on the right track?

You're on the right track.

If all things stay the same, with larger tires you will go FASTER than 
the speedo's indicated rate.

OTOH, changing to lower gears and bigger tires just confuses things.

My '77 had the axles swapped out (3.73s left in favor of 4.09s) before I 
bought it, but it never received the 4.09 speed-o gear box.  Even when I 
put my 31s on for the trip to Seattle this summer, I tried to see how 
close the speed-o was..

I would travel 1.1miles on the Odometer, when the mile markers would only 
read 1 mile.. 10% slower!  

-Tom