OP: It sounds like you've had a lot of flats. Could it be that your vehicles/trailers are overloaded? Or not inflated properly? Or tires not changed out in a safe time period?
We traveled constantly for 16 years including Alaska, all over the country and including your state of Texas and never had a flat on the RV. We checked them before moving and replaced them by age, not looks. We would never attempt changing a big rig tire and full-timers seldom would have room to store a big, heavy tire. They're already carrying everything they own. I would think that manufacturers of the big rigs don't install a spare because of knowing how dangerous it would be to lift and change one. Depending on how big of a rig you get you just may change your mind. Good luck!
