This guide is for general information only and is not legal advice. Laws change — verify current rules with your state DOT or a licensed attorney before relying on this for any legal matter. Read full disclaimer.
The rule
Bicycles are permitted on Interstate highways in Arizona. ADOT permits bicycle travel on the paved shoulders of rural Interstate segments where no reasonable alternative exists, including long stretches of I-10, I-8, I-17, I-19, and I-40. Bicycles are prohibited on Interstate segments within the Phoenix and Tucson metropolitan areas (signed at on-ramps) and through tunnels.
What this means in practice
Interstate cycling is legal in Arizona, but ride only where you have a wide, clean shoulder and exit at the first signed bicycle exit when conditions deteriorate.