There’s a key sentence in the Guinness World Records webpage for longest-running commercial: “The same commercial has been aired continuously every year in parts of the USA.” The word “continuously” is likely more important than it lets on, and it’s clear part of the record relies on the commercial airing regularly and not simply being old and then coming back for nostalgic purposes. While the Discount Tires commercial has aired every year in select markets, it’s possible the Tootsie Pop ad was taken off at some point and then reintroduced later.
Tootsie Pop has had other ads over the years, such as one of the most ’90s commercials ever, where a cybernetic skull and dinosaur destroy a city until a young boy asks them how man licks to get to the center of a Tootsie Pop. With other ads like this airing, it’s possible the original owl ad was taken out of rotation, which would mean it didn’t run continuously. This would give Discount Tire the edge it needs to claim the title.
The confusion is understandable, but it’s best to assume Guinness World Records knows what it’s doing. After all, this organization has monitored all kinds of bizarre records in movies and TV. And until Discount Tire decides the “Thank You” ad needs an update, it will probably retain that record for a while.