The Pima County Department of Environmental Quality encourages monthly tire checks. There are many benefits to this, which are detailed in the news release below: Eco FAQs for National Tire Safety Week Pima County, AZ - In conjunction with National Tire Safety Week, Pima County Department of Environmental Quality Clean Air Program encourages monthly tire checks to improve your vehicle's gas mileage, keep your tires lasting longer, save you money, improve vehicle safety and keep the air healthy to breathe.