I go to my local tire shop - small town so I have one place unless I want to drive 35 miles. They give good service and price although their shop looks like it might collapse any day. Low overhead in more ways than one. As for tires, a major brand like Firestone (Bridgestone still keeps the name for ag) you can get like 3 tread styles in R-1 ag tires not including their radials. Titan took over Goodyear ag but still makes Goodyear tread pattern and Titan tread, also in different tread styles. Before I retired I had a tire mold made for a special compactor tire and was amazed at all the inserts there are in a mold for date codes, plant codes, brand name, etc. Those molds could be used all over the world - kind of a generic mold that fits certain tire plants. Still that is only the final mold for vulcanizing once the carcass is all built up, and that can be by vastly different processes.