The primary contributor of skin color is the pigment known as melanin. The quantity of melanin in the skin varies based on genetic factors and is also dependent on the degree of sun exposure. Melanin is produced by specialized pigment cells known as melanocytes.
Average new tires used on cars typically start with 10/32 to 11/32 of original tread depth. Tires are considered worn out. In most States when they reach 2/32 of remaining tread depth. Ans 2 - Here in Canada (and I'm sure in many parts of the US ) we get a lot of rain.
Here in the U.S., tire tread is measured in 32nds of an inch. A brand-new tire has a tread depth around 10/32nds of an inch (approximately 1/3 of an inch). Some tires, like winter tires or off-road tires, may have a deeper tread. As you drive on the tires, the tread gradually wears down.