I'm putting tubes in all six of them. And yes the temperature swings are always a concern as well. On those -20 mornings you tend to lose a pound or two which isn't too bad unless you're low on pressure to begin with. Thinking back I had tubes in a different machine. The only problem I had was water inside the tire. But that one didn't have metal bolt on stems and was in the water more than on land. The tubes are on order. Thanks