That's what always had me scratching my head about this bike - it always seemed like it came with very slim rims (15mm? Less?) and unusually wide tires (38c) compared to what others had on their 700c wheels. Granted, it's a hybrid bike, but I always wondered why there was such a huge difference in those sizes. Stock, it comes way beyond the Sheldon Brown suggested guidelines.

I was thinking of replacing the tires at some point anyway, because I plan on this being a commuter bike. If I put some Marathon Pluses at, say, 28c and make a switch to Prestas with some sort of grommet, should I be OK?

Also am I understanding the problem right? Here's my side-view drawing...



Thank you so much for your replies, by the way. Here's hoping I can patch that hole in my tube in the meantime, but I doubt I can pull it off. I never seem to have much luck with patching those types of "stress rips", only punctures.