Hypercapnia is an unusually high concentration of carbon dioxide in the blood which may be accompanied by hypoxemia, in which the oxygen level in the blood is low. This condition occurs as a result of poor gas exchange at the lungs which makes it difficult for people to eliminate carbon dioxide from their bodies.
Quick Answer. A tire treadwear rating refers to the amount of time the treads on a tire should last in specific conditions. Tire manufacturers indicate treadwear rating on their tires using a set of numbers between 100 and 700. These numbers indicate how long tire treads will remain safe and perform at their highest capacity.
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.