Shelf-life of a year or two? Only if the manufacturer or retailer wants to convince gullible consumers to purchase more stuff. I'm curious, what was your wife's source for this idea? My experience is that butyl tubes last a long time (I'm talking decades!), whether installed in a tire or on the shelf.

What bugs me about contrived shelf-lives coupled with the "just toss and replace" mentality is that all of these items generally end up in landfills. Why add to this burden when unnecessary.