Tube Sizes
Butyl and Latex are both fairly elastic, so it's not critical to use a tube that is exactly the correct size for your tire. For example, most road tubes are specified as 700x18-23. These tubes can easily be used in a 700x25 tire, or a 27 x 1" tire. The rubber will just be stretched a little thinner than it would be in a narrower tire. If you want thicker rubber, you can use a slightly bigger tube. For example, the Michelin A2 Airstop Tube designed for touring and cyclocross tires which are specified for 700x28/32 can be used with a 700x25 tire. We generally don't recommend this because minimal added puncture resistance doesn't offset the added weight in our opinion. It's also a little easier to make a mistake when installing the larger tube and end up with a pinch flat.