[Richard and Rhonda]

Tuga,

My 95 has a couple more birthdays than yours, and I also see the micro crackes you mention. As part of my ongoing battle with air leaks, those bags have been coated numerous times with soap solution and never have I detected a leak in the bag itself. The rubber is not going to get the UV load that tires get, so they are susceptible to the same degradation. The Ultraviolet is what really kills the rubber.

I am not aware of any recommendations on frequency of replacement that says any thing other than "when needed".

Maybe some of the guys with more vintage coaches will chime in on either still having the originals or when they found it necessary to replace