|This is the way we carried an extra tire. Photo credit: Slowtwitch|
When I toured with my husband, we carried extra tires by folding each into a figure-eight, then strapping these onto our panniers. We didn't always purchase Kevlar tires, but any tire was "foldable" or fashioned to be smaller.
I prowled the Internet to find out the scoop. Livestrong.com has the most informative answer. Basically, all tires are beaded; the "bead" is the fabric-covered cord that makes up the inner circumference of the tire. Its function is to secure it to the rim. Lighter weight Kevlar is stronger and folds easier versus steel bead which is less expensive, primarily used on bikes sold on the showroom floor. Steel bead isn't an inferior product; it just means it will be heavier (approximately 2 oz.)—and if you understand that—it may actually be a financial advantage to buy the cheaper tire, especially where the minor weight difference isn't an issue.
|Look at how small this baby can get! Photo credit: FatBmx|
From what I can discern, in the last ten years "foldable" tires (like the one pictured above) are fetching higher prices, marketed to bike tourers who carry an extra tire for backup as they literally can be folded and not looped. But come on, if you are on tour, hauling pounds of gear, what does 4 more ounces really matter? Fixed bead tires can also be looped into 3 tight circles as described here on Sheldon Brown's site, which suits me just fine.