The key point for tire storage, on or off the bike is that they aren’t on the ground or under load. And the bike or bikes are in a garage year round. Not outside under some tent or bike cover.

You can visibly inspect them. Rotate them with your hand. Do you see cracking or imperfections in the rubber? If the answer is no, you are probably fine. I’d ride it gently at lower speeds. If you don’t feel anything off then good to go. I’d do what I always do before every ride. PSI check, add air as needed. Rotate the tires with your hand and visibly inspect for anything. If you are willing to do that every ride, you’re fine. If they are going bad due to age, you’ll get a crack, that you can see visibly. It’s not like you are going to be on a ride and the tire is going to blow or deform all at once. It’ll be a crack that shows.

I’m pretty anal about all this and I will still use a helmet longer than 5 years. Like engine oil, for me, it’s about use, how much of it, how much sweat etc. Between seasons (we get 2 months of hard cold where I don’t ride) I’ll put my cheek pads out and just know from doing this way too long, that when my helmet doesn’t fit snug tight like it used to, it’s time for a new one. That’s usually about 7 years for me. And that’s with putting new cheek pads in at some point due to sweat. I know guys that are anal retentive about tires. When they buy them, if they are say 2 year old production tires, they’ll have them exchanged. I don’t worry about such things. I have a two tire racks in the garage on the walls. One for my performance car winter wheels. The other is for motorcycle tires only. I’ll buy sport tires for my liters when I can get them at a steep discount and store them on the rack. They are wrapped up in that plastic stuff you use in the kitchen for food so they aren’t exposed to air. And I have no problem mounting a 5 year old manu’d tire because they are mint new.

So like many things, the truth is in the middle of total anal retention and fuck it I’m not worried about anything.

I am a original owner of a 1980 Suzuki GS1100 with about 5k miles on it and probably on my 4th set but the last set has been on close to 15 years…thought about replacing it last year due to age but didn’t