Primes, even peaks vary. not nec tied to age.
30+ primes - Tilden (peak), Gardnar Mulloy (peak), Segura (peak), Drobny, LAVER (peak) Rosewall, Ashe (peak), Agassi, Wawrinka (peak), Djokovic, Gonzalez; arguably von Cramm, Bromwich, Kozeluh, Borotra, et al.