jOHNsnr.
Pack Dog
BMW recommends replacing your Helmet after 5 Years.I am not an expert but perhaps in the interest of safety (your helmet is afterall your most important safety item) we could hear from someone knowledgeable on this topic why it is advised to replace after 5 Years.i Assume that the material inside the helmet deteriorates and loses its value to protect your biggest asset (Head) hence the 5 years.