Joined: Aug 2004
Posts: 2,784
Likes: 63
From: Prague, Czech Republic
Bikes: Time ADH01, Merlin Extra Light, Orbea Orca, Ritchey Outback,Tomac Revolver Mountain Bike, Cannondale Crit 3.0 now used for time trials.
To the OP, rather than going with the wide range of comments here, from 2 to 22 years, contact the manufacturer of your helmet and ask them. For me, my newest Giro is 3 years old, and the other Giro is 7 years old. Have replaced padding in both a few times.