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Temporary spare

What is the min psi that you car safely drive on for a temp spare. The tire says 60 psi but most are neglected and never have that much.

That pressure is the safe pressure to make it last at least 60 miles. Lower pressure will quickly destroy the already marginal tire.

If the temporary spare is neglected it’s the owner’s fault. An under-inflated mini spare is probably not a safe thing to drive on until it’s been properly inflated.

Interesting question. I just used my spare Fri night on a very sensitive AWD Subaru. I skipped checking air pressure as my 2 yr old with me during flat fix was quite fussy and ready for bed.

I drove 8 miles on it at 40mph with only 25psi(checked latter) instead of blaring 60 psi. I could feel the car dragging and slight clunking as rear differential is limited slip. An hour latter my rear limited slip diff was still hot to the touch.

It works fine after getting my tire fixed thankfully.

My mini spare gets inflated to 60 PSI once a month and before each long trip. However, on long trips I also carry a full-sized spare since the miniature spare is only meant to get you to the nearest tire seller.

Don’t Subarus have a fuse that you have to pull (or insert) when using the compact spare? If you didn’t do that, you probably did some costly damage that will show up sooner or later.

I wouldn’t drive on one that’s under 50 PSI (and I’d drive even slower if it’s that low), but that’s just my uninformed guess.

I always overinflate my spare tires when checking them. You can always let out some air at roadside if needed, assuming you have a gauge in the car. For a full-size spare, I go to the maximum pressure listed on the tire. For a compact spare that calls for 60 PSI, I go to about 65 PSI (which should be safe, since that’s probably what a properly-inflated tire goes to when it’s hot).

Remember too that if the tire is stored in a well, in the back, in the winter, to always go a little higher by a few lbs. I wouldn’t worry about plus or minus 5 lbs around 60…but not go much below 55 psi. You can’t get away with much below if you’re carrying a “full load” either. That makes a huge difference in pressure safety.

Mini spare tires should be checked and inflated to 60psi as necessary, AT LEAST every six months.
In the past 15-20 years of doing this for 6 different vehicles, I have noticed that a brand new/never used mini spare tire, will lose at least 15 psi of presure in a six month period. So probably, an even safer thing to do is to check for pressure drops every 3 months.

Also keep in mind that when you get your tires balanced and rotated, even if they check the pressure, they don’t bother to check your spare 99.99999% of the time.

This is just one of the reasons why I always carry an electric tire inflator that plugs into the cigarette lighter socket. They are not that expensive, and it frees you from having to drive to a gas station where the tire pump may not even be accessible.