Off with the tyre and hand inside and found several thorns that were about to come through. Reverse the tyre and pull out all the thorns
One of the first things I did was turn the tires inside out and run my hand over the entire inside surface to check for thorn tips that couldn't be seen/felt from the exterior. I found approximately 8-10 or so in each tire. With so few spare tubes, and all the popped tubes basically looking like swiss cheese, and not worth patching, I didn't want to risk putting any holes in the spares.