You need to meet the mandatory state requirements for car insurance.
Arizona, like all states has set a minimum requirement for car insurance. This requirement is intended to protect you and everyone else you may encounter from paying out of pocket in the event of a vehicle collision. There are an abundance of costs to consider including property damage costs for repair to vehicles or structures you might collide with and medical costs in the event someone is injured as a result of a vehicle collision.
Fortunately, the Arizona Department of Motor Vehicles makes their requirements very clear and posts them at their web site:
Arizona requires that every motor vehicle operated on our roadways be covered by one of the statutory forms of financial responsibility, more commonly called liability insurance, through a company that is authorized to do business in Arizona. This includes golf carts, motorcycles and mopeds.
Minimum levels of financial responsibility are:
$15,000 bodily injury liability for one person and $30,000 for two or more persons
$10,000 property damage liability
Failure to maintain proper insurance could lead to the suspension of your vehicle registration and/or driver license. To reinstate these privileges, fees and future proof of financial responsibility must be filed with MVD. The future proof requirement is most commonly an SR22 form from an insurance company. This can be expensive to the vehicle owner, especially since the law requires the owner to carry the SR22 for three years from the date of suspension.