A tire can still show plenty of tread and still deserve a closer look. Tread depth matters, but it tells only part of the story about whether a tire remains safe for the road.
That can make a tire-shop recommendation feel suspiciously convenient. Four tires can represent a hefty bill, especially if the car otherwise drives perfectly. Before assuming the shop simply wants your money, ask what specific condition triggered the recommendation. A legitimate inspection should uncover something concrete.