85 octane is the correct grade for most vehicles operating at this altitude and above. These are questions you should answer more frequently during the summer. Neglecting these items can be life-threatening during these times of extreme heat. Many people wait until fall to replace tires, feeling winter traction to be the primary purchase consideration. Stop and think how many vehicles you see on the roadside during hot weather with failed tires.
Summer heat causes many tire failures.
Look at the recent issues with Firestone and Ford. The tires overheated when run soft according to Firestone and failed. Heat is an enemy of batteries. Many batteries over the years have been protected by insulating blankets or plastic shrouds to help control temperatures. Most battery failures occur in summer heat or winter cold.