Originally Posted by
CrankyOne
My tires are 700x45 (47-622). Bike shops here all stock either a 700x35-42 or 700x37-43. Nothing larger. All say these will be fine. At least a couple of times when I'd encountered this in Europe the shops were very much against using undersize tubes and would recommend going to another shop if they didn't have the right size. They said that stretching an undersize tube causes much faster natural air leakage (instead of having to add air once every three months you'd need to add it about once per week) and seemingly they flatted easier.
Any truth to this?
I have a pair of 45s I use on one of my bikes and I have a set of tubes for them that fit a large range of tire sizes (like 35 - 47). I probably got them online but I don't know for sure. It might have been at "One on One" downtown or at the Hub Coop.
FWIW I had a tube sized for 28-32mm tires inside a 35 for quite awhile. It was supposed to be temporary (like a few days) but it was probably more like a few weeks. Since tires sizes are not very exact I'm guessing that a few mm isn't a big deal. However, I personally would rather stick with the recommended ranges if at all possible.