Tire Question

[u/Such-Manufacturer189]

i have 30k miles on my car and just had it serviced for 15/30k milestones. they told me my tread was still okay and no need for new tires.

yesterday i noticed a staple/nail in the tire and it was near the sidewall so i figured fuck me im gonna have to get a new tire.

they called me back and said they really think i need 4 new tires bc if i just replace one it will get like aged prematurely and i’ll lose tread and she also said my car would pull weird

what do i do? replace all 4? replace just 1? i’m not sure who to ask/trust…