^ What trader4 wrote...
the diff on 225 vs 235 in OP's size is nominal.

And, Ibid on the interstate mile marker with stopwatch test. Do it a few times, steady on the speed.

Not sure I agree that most GPS units are spot on, in terms of speed.
GL, mD

__________________
Ol'UncleMotor
From the Home Base of Pro Bono Punditry
and 50 Cent Opins...

Our Mtn Scenes, Car Pics, and Road Trip Pics on Flickr:
http://www.flickr.com/photos/4527537...7627297418250/
http://www.flickr.com/photos/4527537...7627332480833/

http://www.flickr.com/photos/45275375@N00/

My X Page