Thanks, I should have known to look in the Sheldon Brown links..... As usuall, I've learned a lot through the answers. I looked on the rim and found 622-19, in REAL LITTLE print. The Sheldon graph shows that 28 is indeed the most narrow tire to run. I guess I need to look for some new wheels while I still have life in my wider tires.

I did mention "resistence" but as I guess things go hand in hand, I think weight reduction is the main goal.

Thanks.