I'd suggest touring/city type of tires by Continental: Travel Contact, Top Contact or Touring. Their vectran is like kevlar. Alternatively you can consider Schwalbe touring/city: Marathon Plus or Marathon XR. You need 26" diameter and you can read the width off your current tires. The tires I mention require tubes, but do not go flat. I have no experience with tubeless or airfree. The last technology has been tried many times and has not taken off in any of the preceding attempts.