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.
Tread Depth. Tread depth is a vertical measurement between the top of the tread rubber to the bottom of the tire's deepest grooves. In the United States, tread depth is measured in 32nds of an inch. Because it is difficult to accurately measure tread depth with a ruler, tread depth is best measured with a tire tread depth gauge.