RGV_Z28

iTrader: (7)

What exactly is the aspect ratio? And what is it on a 2001 Pontiac trans am with stock rims and tires. thanks

jimmyblue

iTrader: (11)

Aspect ratio is height divided by width. A 275/40R17
has an aspect ratio of 40% (0.4) nominally. I don't
know what came stock on a Trans Am, which model
and options.

If you're looking at touching up a speedo setting,
the best accuracy would come from driving onto a
tape measure so you could wrap it around the tire
and measure circumference, hence have true
distance per revolution, diameter etc. all figurable
from that. I reckon all of the different tire options
are slightly off from nominal (then too there is the
new vs worn change in circumference).

RGV_Z28

iTrader: (7)

Thanks, but once I get the circumfrence, where would i go from there.