Spare tire pressure?

Hey all, stupid question time: is there any reason to keep the spare tire overinflated?

I just got home from the dealer where I had them checking a leaky tire. They're going to have to replace the tire (puncture reeeally close to the sidewall, damnit, no repairing that), but that's not my question. As I was driving home, I was surprised to see the TPMS warning not on: I didn't think the spare tire would have a TPMS sensor, and I assumed I'd be getting warning lights until the new tire comes in and they re-mount it later today or tomorrow.

But when I flipped over to the TPMS screen, I saw that it was reading the pressure in the spare, and it was really high: 47 PSI. As far as I can tell, the spare is the exact same tire as the rest of them (I'm still running the OEM Goodyears), so I don't see any reason for this. I just let air out until it came down to the recommended pressure, but I figured I'd check to see if there's some weird esoteric reason for keeping spare tires overinflated by 50% that I didn't know about.

 

I always put like 10-15 extra psi in my spare so that when I need it'll still have like 25 in it. not something thats easy to check since theres no tpms in mine.

Edit: To add you lose about 2-4 psi a month. First cold snap we had here I lost 5psi in all 4 tires over night.

 

That is my experience with Goodyear tires as well, they will slowly lose air pressure and need to be topped off every month. I have not had the same experience with other brands even on the same wheels.

 

I put 40 in my spare. I check it every few months when the seasons change usually when I need to adjust my tires so I do them all at once.