Depends on the car and spare. On my car the spare is a much more thin tire compared to my regular ones. It’s meant to act as a short-term fix to get a proper tire back on. This type of spare isn’t meant to be used long-term.
Since it’s a different form than a typical tire, many spares (mine included) are almost double the PSI (~60) than my typical tire.
I’d say just make sure you check on the tire itself! It’s definitely likely it’s different from the main tires for many makes and models.
I’m going to build my own Reddit, with blackjack and hookers!