Installing larger rims/tires...

[Chuck Simpson <csimpson@zeltech.com>]

I'm not sure if this pertains to our cars, but I was
watching "ShadeTree Mechanic" on TNN this weekend
and they were installing larger rims and tires on a truck.
The first thing they mentioned was how installing larger
rims and tires can really screw up the speedo system
and the transmission.
They mentioned the speedo will need calibrating, so
they bought some box that was attached to the chassis
and sensor and automatically re-calibrated the speedometer.
Then they bought some device that captured signals
from the torque-converter and made necessary adjustments
as needed.  It kind of looked like a 2-foot cable running
through a small box in the middle.

Does anyone running 16+ inch rims have problems?
Or how do you get your speedometers re-calibrated?

I believe they mentioned the truck was an automatic,
which may have had a much greater impact on shifting
and how the gear ratios were changed by +1.10%.
I just wonder what affect the change would have on
a manual transmission.

j/curious,

-Chuck Simpson
'98 White Jetta GLX-VR6