Getting my MXT's put on at America's Tire Co, aka Discount Tire Co
outside California, I watched a flat being repaired from the inside
out with a drill and the mushroom shaped patch.  Asked how much to
fix a flat.  "Nothing".  OK that's if you sell the tires.
How about if it's a tire from some other company?  "Nothing".
Verified this with two people. They fix any flat for free.
They're such quick, friendly   people,  it's a marketing tool
because it's fun to go back there and talk to them.....and buy tires.
Many shops in the midwest, southwest, and west....USA.

Cheers, Tom Neal