Out of state visitors must still purchase an OHV decal for ATV use. However, you can avoid purchasing a decal if you meet ALL of these exemptions: You are not a resident of Arizona, you own the vehicle, you display a current OHV decal or registration from your home state, and your ATV is not in Arizona for more than 30 consecutive days.
Check out these Petrified Forest Natl Pk, AZ ATV/OHV resources: