Mine was stuck in the car haulers lot for three weeks because of a flat tire and I have three tires with a red dot and one without.Mine is a Lariat 4x4 502 PB. It has the chrome package and 6.5 ft box.
Tire size is a 275 65 R 18 116t.
They also have the annoying red spray paint dot on the side wall.
I believe that this is done to show that they are from the factory not purchased from a tire dealer.