[rescue] SLACKERS

[Kurt Huhn]

> Do larger tires affect the accuracy of the speedometer?  If not, how
> does the speedometer on most cars determine speed?  It would make most
> sense to me to have it judge the RPM of the axle, and determine speed
> from that, but, if the circumference of the wheel changed, the
> speedometer would be inaccurate.  So, do you have to adjust the
> speedometer if you put on larger tires, does the speedometer gague speed
> a different way, or is the change in circumference of the tire not
> usually big enough to make a difference?
> 

Yes, totally.  Your speedometer and odometer are set with a formula of
tire size and rpm.  If you change the tire size, your speedometer and
odometer will be off be a coresponding amount.

Poop, I lost the link...I think the DML website has a good
calculator....here it is:
http://twistedbits.net/~jon/WWW/DAKOTA/TIRECALC/tirecalc.html
It's one of the better ones out there - it gives tire size difference,
speedometer error, odometer error, and effective gear change.

Kurt