Is there a recommendation on how often you should replace plastic ramps? If the ramps look visibly damaged or warped it would make sense to buy a new pair, but I'm curious if the structural integrity of these kind of ramps degrade with age and thus require replacement?
I think it will vary based on storage conditions and exposure to UV light. This type of damage is often hidden and undetectable. The key problem might be that they will fail with out notice. If they are 10 years old I would replace them for safety sake.