Tire tread depth
Tires are the determining factor for a pleasant ride, as they are the contact point between the car and the road. Your tires’ ability to function optimally is primarily influenced by tread depth.
Depending on their type, new tires have a tread depth of between 10/32” (7 mm) and 12/32” (9.5 mm). This ensures the best performance in changing conditions. While the minimum legal tread depth for all passenger car tires in the US is 2/32” (1.6 mm), it is safer to replace them at a depth of at least 4/32” (2 mm). For winter tires, it is recommended that you replace your tires when the tread depth is below 15/64” (4 mm). Weather considerations mean that the wear limit is set at 5/32” (4 mm) for winter tires. Winter tires with less than 5/32” (4 mm tread) depth in principle cease to be winter tires.
The tread on the tire features a Tread Wear Indicator (TWI) which shows when a tire is close to the wear limit.
The risk of hydroplaning on wet surfaces rises as your tires approach the minimum tread depth. While it isn’t possible to determine at what tread depth any tire type can be safely driven on wet surfaces, there are several precautions you can take to decrease the risk. In general, wider tires have a greater risk of hydroplaning when the tread depth approaches the minimum. In order to get the longest possible use from your tires, it is recommended to switch their position on your car from front to back and vice versa around the 4,500-6,000-mile mark. Once rotated, be sure to adjust the tire pressure to the new position of the tires. Taking these measures will increase the lifespan of your tires and improve driving comfort.