Everything about the SR 71 was important and thought out when a problem occurred, and Lockheed provided the answer. SR 71 tires …Workers used aluminum on the areas where the wheels retracted and added latex. Then they filled the tires with nitrogen.
The tire pressure was 415 pounds per square inch compared to the 35 psi in your car. With all the high speed that SR-71 Blackbird would fly, it caused the tires of the aircraft to also get heated up immensely just like its airframe, despite the tires being housed inside a cell. If these tires were inflated with normal oxygen, then it would have seeped out of them even while the landing gear was being retracted.
Tires made by BF Goodrich
I have over 700 flight hours in the A-12 and the SR-71 and never had a tire blow out. There are three tires on each side. We used brake coolers after landings because of the heat generated during flight and landing. The tires were normally changed after 10 takeoffs, because the wear & tear & heat is during the time of rotation with a full fuel load. When we could we took off with half fuel load and air-air refueled shortly after takeoff. That reduced the takeoff weight by about 40,000 pounds. The fully loaded SR-71 weighed about 160,000 pounds. I don’t believe that we had a tire problem. Quoted by Colonel Ken Collins, A- 12 and SR -71 pilot.