So I'm not crazy, thank you. This is like the closest thing I could find to the subject, or I'm asking the wrong question on google
Fuels and Fuel Delivery
Fuels sold in Colorado and other high altitude states in the West, are generally 2 points lower in octane. Simply buy the same grade of fuel you were used to buying at low altitude. For example, if you had 87,89, 93, octane availiable in New Jersey, your choices in Colorado now are 85,87,91. If you were okay with middle grade 89 octane, your choice in Colorado will now be the middle grade 87 octane.