I have towed over 30,000 miles in the last 3 1/2 years. I have had five flat tires while towing.
1. Truck rear from rock puncture at Glacier National Park. Changed tire myself repaired at local tire shop.
2. Trailer tire right rear in South Dakota, slow leak caused by nail. Changed tire myself, repaired locally when I got home.
3. Truck rear nail type puncture at National Grass lands, changed tire myself. repaired tire locally when got home.
4. Truck rear in Indiana, piece of scrap metal pulled from tread. Repaired locally when I got home.
5. Trailer tire, on Interstate coming from Florida. Hit road hazard large enough to put baseball sized dent in rim, bend the axle and break a leaf spring. Roadside assistance needed to load TT on flat bed to haul to Camping World for repair.
The first three flats were on my first set of truck and trailer tires, the last two were on a second set of truck and trailer tires that were less than a year old.
I routinely monitor tire pressure, have the truck tires rotated, the first set of TT tires were C rated the second are D rated. None of these issues were due tire failures, they were due to road debris.
Also, it is important to have the tools and knowhow to fix a flat tire.
Moral, if you are going to tow; This stuff is going to happen.