As Jan mentioned, many Russian aircraft have traditionally been designed for operation from unpaved airstrips. Even fighters like the MiG-25 or the MiG-29 have (relatively) low-pressure tires (10 bar / 150 psi) which allows their operation from unprepared airstrips. The MiG-29 can even close its air intakes to prevent foreign object damage, sucking air through louvres on the upper wing. Here is a picture of the intake of a Polish MiG-29 in take-off configuration, taken from
this website:
With the MiG-25, you could take off from a grass strip, climb to FL800 and fly at Mach 3, and land on that grass strip again. Fascinating!