For 1965, all cars were required to make a minimum of two pit stops. A pit stop was generally defined as coming to a complete stop in the respective pit box, and hooking up the fueling mechanism. Tire changes were not specifically required, and some cars in fact changed zero tires all day. On-board fuel tank capacity was reduced to 75 gallons, which also included requirements that they contain rubber bladders inside, and were required to be behind the driver on the left side of each car. Crossover tubes were no longer allowed ahead of the driver as well. Pressurized fueling rigs were also outlawed. All fueling rigs from 1965 onward had to be gravity feed, a rule that still is in effect as of 2020.