Mean Time Between Failures (MTBF) is a standard measure of reliability.
Compared to 1970 tech tyre, kevlar protected ones have much longer MTBF. I would estimate MTBF for old tech to be about 3-6 months and for modern everyday tyres, 12-18 months. High protection tyres such as Schwalbe Marathon Plus are effectively puncture proof, inc small tacks and pins but fail with massive metalwork.
MTBF will vary according to local nasties such as goat head thorn or flint shards.