Especially since neither Pontiac nor Chevrolet indicated brand or model of tire on the order sheet, only style and size. Therefore, there would not be a code for Goodyear vs. Firestone.

RWL does have a different code than redline, white stripe, or blackwall. A copy of the billing history will give the tire code.

One new car we bought had a different brand tire on the spare than on the road wheels, as are our space saver spares. It was on a plain rim so it did not matter as it was not going to be rotated.