Take a wheel off. On the inside should be the size of the wheel. Mine have the offset noted too.
I did find the names of the various wheels (at least what they are called in Canada):
16" - for the Trendline: called the Portland
17" - for the Comfortline: called the Philadelphia
18" - for Comfortline Sport (what OP has): called the Pasedena
18" - for Highline: called the New York
19" - for Highline Sport: called the Savannah
This doesn't help with offsets of course but at least you have a name to go with...
Edit: apparently there are a couple of optional wheels in Canada as well:
16" - Baltimore (5 fairly thick spokes)
18" - Davenport (10 thin spokes arranged in pairs - like Savannah but thicker and smaller wheel diameter).
Last edited by markk900; 08-12-2012 at 11:27 AM. Reason: Found more info