Rear End Ratio question

Tjhoward84 said
245/40-18s

I just have the speedo calibrated and it's pretty close to accurate.

According to this site

http://www.audiworld.com/forums/tt-mk2-discussion-120/tire-diameter-chart-2704424/

Those tires are 25.7" in dia

There are tons and tons of mph / gear/ speed / rpm calculators on the 'net

"Wallace" is just one
http://www.wallaceracing.com/Calculators.htm

http://www.wallaceracing.com/gear-speed.php

Which generates this chart

and that means "something is wrong." Either you don't have a 3.54, or the tires are different, or the speedo is wrong, or you have a converter with a VERY high stall

Cheapest easiest way in my opinion, in this day, is to use a GPS for speed.