Winter tires can wear out if used in prolonged hot conditions, and summer tires have lower resistance in slippery conditions. Customers who invest in seasonal tires will likely ask you when they need to change from their winter tires to their summer tires (and vice versa).
The magic number is 45°F. When temperatures are consistently above that mark, drive on summer tires. When temperatures are regularly below that mark, make the switch to winter tires. During each changeover, a technician should check the TPMS valves and sensors on all of the tires.