Tire scam in Utah

Three years ago after eating at the Mcdonalds in Williams Arizona I pulled across the street to fill up at the Mobil station. While I was filling up I noticed a man cleaning the pumps faces with windex. When he got to the outside pump that I was fueling at he told me that it looked like one of my tires on my MH was low in air and offered to check it for me. Being suspicious I declined and told him that I would pull across the street and check it myself after fueling as I religiously check my tires and none had shown low before. He told me that it wouldn't take long at all because he owned the Firestone tire shop not 15 feet from where I was parked and I could just pull up after fueling and he would check it for free. So I thought what the heck he seems like he's just trying to help and I figured I would watch him like a hawk. After I moved forward he had another guy come out of the shop to check my outside dual on the left side and said he would check the other side while I was there. So now I found myself trying to watch both sides at the same time. He tells me that he was wrong that all the tires were ok inflation wise but one of them had a screw in it and he would fix it for me if I wished. Still not knowing whether I was being scammed after I saw that there was indeed a screw in it I reluctantly told him he could fix it figuring the most he would get out of me was a flat repair. After unmounting the tire he told me that the hole was in a bad spot and he may have to replace the tire. At this point I asked to see the screw that was in it. He went back to the dismounting machine and came back with a screw that wasn'nt even 1/4" long. I told him I was surprised that a screw that short would even get through the tread and he told me that it was right where the sidewall and tread came together so it was thin there. At this point I started purposely acting suspisious and agitated and assured him that I was confident that his patch would work. I think he knew by now that he had better back off a bit. After he patched it he told me that he had checked his stock and din't have my tire size anyway (patch has held for the last 30000 miles). He then charged me $30.00 for a flat repair and when I tried to pay with a credit card he told me that he didn't take cards. When I asked him how all the truckers paid when he took his service truck on the hiway he told me that all the truckers had purchase orders with them for occasions like that. I went away from there almost positive that I had been scammed but could not prove it. By the way before I drove out he let me know that my shocks looked bottomed out and should probably be replaced. A couple of weeks ago we were in Williams needing gas and went to the Chevron across the hiway and paid more just to avoid that area all together.