Max PSI should be listed on the outside of each tire.
Assuming they're the Pirelli Cinturato tires in the size you mentioned then max PSI is 50 according to TireRack:
https://www.tirerack.com/tires/tires...LMOE&tab=Sizes
With that said, I don't ever run the max, however, if you're at 31psi then not surprised the light is on. My recommendation would be to fill them to around 40-42 PSI or until the light goes off.
Everyone will have their specific preference for PSI ranges so the main thing you want to do is get enough air in the tire so the light is longer on without overinflating them like you mentioned.