From the thread title I was expecting something drastic, those cuts are nothing to worry about - if the casing is damaged the tyre will usually develop a wiggle when it is spun and viewed from above. I would recommend deflating the tyres and exploring the cuts with a pointy thing to be sure there's nothing still in there that might cause further damage. If you're worried you can take them off and check internally for signs of damage to the casing. Having said that, tyres deteriorate with age even when they're not getting worn and cut, and those don't look fresh - they probably don't grip as well as they did when new, it may be time to start thinking about what your next tyres will be. Buy the replacements while these are still good and you may not need them for years.