Everything about the SR-71 Blackbird was unique even its tires. SR-71 Blackbird spy plane was the fastest plane ever that can cruise at Mach 3+
Flying more than three times the speed of sound generates 316° C (600° F) temperatures on external aircraft surfaces, which are enough to melt conventional aluminium airframes. That’s why the SR-71’s external skin is made of titanium alloy, to shield the internal aluminium airframe.
But the tires, which retracted into the wings during flight, also had to keep from melting!
Related Article: When two SR-71 Pilots ejected at Mach 3 due to Midair Disintegrating
In the Video below Museum docent Scott Wiley reveals how the SR-71’s tires keep from melting.
Why are SR-71 tires silver?
Aluminium was mixed in with latex when the tires were created that gives them the very distinct silver colour.
The tires were impregnated with aluminium dust to reflect heat and inflated with nitrogen to control heat expansion and prevent possible tire explosion at altitude. By inflating the tires with nitrogen, instead of air, a fire would be less likely to start due to the absence of oxygen.
The tire pressure on the SR-71 was 415 psi (compared to the 32-35 psi in your automobile tires!).
Each tire cost $2,300. These 22-ply tires, used on the main landing gear of the SR-71, had a general life cycle of 15 landings. When the tires wore down, red chords became visible, signalling the replacement of the tires.
The tire on the left is relatively unused, while the tire on the right had its red chords revealed long ago with a bit of ply missing!
The Hill Aerospace Museum has one of the SR-71 tires on display.