As Kemo & Fin said...learned this from bicycling for crying out loud...tires, tubes and rim tape are a blend of RUBBER, and takes only a couple years for rubber deteriorates not just on the skin surface, but internally. Just leave a rubber band, like a bungee cord strapped on the back of your seat under a bit of tension...turns into a crumbling mess in about a year or two. Do you really think a motorcycle setup used year around, or intermittant (which would extend the "wear out" component...would last "longer?" Trust me, if you still have the tires on after 5 or 6 years, check the sidewalls, if you see "checking" or microfractures but still have tread, change the works...sudden failure is not something to roll the dice with.