There are no guarantees. They might make it, they might not. I would bring an extra tire and tube on a loaded tour anyways. I have some tires from the eighties on my spare bike and the white sidewall rubber is flaking off in some spots. I have bombed around town on them occasionally for the past few years and they have held out. The cords are still in decent shape and are not abraded. The strength in tires is in the cording. The outside rubber helps protect the cords from abrasion and the inner rubber seals them so they don't leak. If you took the cords out of the tire, you probably could not inflate them past five or ten psi before they burst (kind of like inflating a bike inner tube when it is not encased in the tire and rim assembly).