LOL - since the name of the thread is:
ISO best dang flour tortillas - I'm guessing flour.
Well, LT - there are several things that can contribute to your problem:
Altitude by itself may not be the problem ... but the humidity in your location can be a factor. But, even down here in the humid flatlands ... some things make a difference.
INGREDIENTS: use all-purpose flour - not bread flour. Strong flours like bread or whole wheat require more liquid in the dough - and even if you are using AP you might want to add 2-3 Tablespoons more water to the recipe to compensate for that the environment is sucking out of the dough.
TECHNIQUE: They need to be cooked quick over a hot griddle - something like a blazing hot cast iron griddle ... not an electric griddle.
STORAGE: If you're not going to serve them
immediately after removal from the griddle - you need to store them in a way to retain the heat and moisture - like wraping them up in heavy duty aluminum foil. One trick restaurants use is to store the tortillas in a "steam cabinet" to keep them hot and moist - actually adds some moisture.
RESURRECTION: Depending on how you are using them ... you can take about 4 tortillas and put them between two damp paper towls and run them in the microwave for about 30-seconds and then let them sit for about another 30-60 seconds before you remove them. Another way is to use a
splatter screen over a skillet of simmering water.
Hope this gives you some ideas ....