I have the original pair of Schwinn Puff 27" tires that came on my '80 Traveler still in service. I use them as my winter stationary trainer tires. They are perfect for this. They show no cracking whatsoever.

That's great that you've found a good balance between riding and wrenching. I still tend to take in too many projects--- which end up clogging the shop as they wait and I dream. I have at least three builds bubbling in my head at the moment, two wheels with broken spokes which need repair, and a flat to fix. I'm also helping a teen from church with a MTB restoration, and have two church member's bikes which need service and adjustments.

All that makes it sound as if I don't ride much, but the last few months I've managed about 300 miles per month. I'm heading out shortly for a 60 mile gravel grind with a buddy. We'll be on our mid '80s Schwinn High Sierras. Cant wait!