Originally Posted by
coachcommute
If I swapped the tires wouldn't I have to buy new wider wheels too?
No. Rims will take a pretty wide range of tire widths, and even narrow road bike rims can generally take up to a 28 mm tire. I don't know the rim widths on those bikes, but if you ever find out, you can use a chart like the one on Sheldon Brown's site as a guide for acceptable tire widths:
Tire Sizing Systems
But keep in mind the rim often isn't the limiting factor when it comes to tire width. If you want to run bigger tires, you need to make sure there's enough fork & frame clearance to fit them. A number of newish road bikes can't comfortably take bigger than a 25 or
maybe 28 mm tire.