Originally Posted by chas58

Good call. Thanks again! So, I went and bought some calipers and tires...

Trimmed the knobs off the Kenda Kwick Cross 700x30, and it worked fine (although cornering hard at 25mph is a bit hairy with the knobs on the front tire).

Michelin Pro4 25mm, 28mm and Conti 4season 28mm all measure the same size (27mm as I recall).
How about that. A 25mm and a 28mm tire - same model and brand, are the same size (the 28mm does have a wider tread for lower pressures I presume)

GP4000s 28mm and Gatorskin wire bead 32mm measure the same at 29mm actual width.
How about that 28 mm and 32mm tire from the same manufacturer are the same size!

A new folding gatorskin 32mm measures 30mm actual width
A super rare conti 4 season in 32mm measures 32mm actual width.

That 28mm Conti GP4000s is an amazing tire. Light, very supple, sticky. I love it. Too fat for my rear, I need a smaller 28mm for the rear, but it makes a wonderful front tire.