I have some Metro Duro's (26X1.5) on my bike. They are great tires...kevlar belts...carbon fiber sidewalls (I read that on one site but can't find it now) and a steel reinforced bead. Anyway, the tires are now about 7 years old and the side walls in particular have been giving me problems. I tossed another tire because there was a huge bubble in the sidewall that looked like it was going to pop any minute. I replaced it with the same kind of tire off my wife's bike. Everything was going fine (300-400 miles) then I noticed a very small bubble forming on the front tire again last night. I rode it today without problem, but I checked when I got home and it was not huge...but noticeably bigger. The fibers in the side walls are starting to split. Is it worth chancing for another day or is this not something you would risk? The other bubble was huge and didn't pop.

Also, do you think this has more to do with the age of the tire than over inflation? I inflate to 85 PSI...the tire is rated for between 50-100 PSI. Thoughts? I hate missing a commute day! Argh! Lastly, does it help to 'condition' the sidewalls with Armor All or something like that? Would that have prevented this break down of the material?