Twice left out to dry.
Bring tyres and wheels appropriate for the ride.
If there is any question, bring heavier and bigger stuff. NEVER lighter and smaller.
Deep Dish rims on training rides are stupid. They add to several problems.
Always have a spare tube, a tool, and a pump. ALWAYS.
A chain tool is also highly recommended.
If you can afford fancy stupid wheels then you can certainly afford a saddle bag for all your bikes.