I need to inspect my tires also. Have 2025 miles on them. There are slits in places, and when I look them over I can't tell if there are things caught inside or not. I've tried looking out in the sunlight where the sun would reveal things, but didn't see anything. Have been a few places where I could see something in there, but it looked like part of the rubber of the tire.

So, questions:

How long before I should replace the tires?

How do I know whether a slit is truly clear or not?

A cycling friend told me of a trick he uses to keep the slits sealed on his bike. Says it gives him about 25% more use out of his tires. After inspecting his tires to make sure the slits are clear, he puts a little amount of super glue in them. Have any of you tried this?