Spare Tire Inflation

Messages
298
Location
The OC
Any issue with inflating a spare tire up around 50 lbs. as it sits under my truck. This way I don't have to worry about it getting low on pressure.
 

JHZR2

Staff member
Messages
44,860
Location
New Jersey
I guess the question is what is the addition with repect to air pressure when loaded and mounted, vs. unloaded. I believe that if one does a force balance, all pressure or variations should effect the shape and allow a consistent pressure to be maintained, even if pressurized without a load on the wheel/tire. Capriracer likely has the fast answer...
 
Messages
9,571
Location
Ontario, Canada
 Originally Posted By: bdcardinal
i always put spares at max inflation. cant count how many i would check and they would be at 0psi.
+1 50 psi probably won't hurt anything but if you have an old old spare with a 35psi max then it might not like being 15 psi over for a few months... Just keep it at the max on the sidewall and check it when you change the oil. Or carry a hand pump like me. Ian
 
Messages
39,811
Location
Great Lakes
 Originally Posted By: JHZR2
I guess the question is what is the addition with repect to air pressure when loaded and mounted, vs. unloaded.
The PSI in a tire will be the same, regardless if it's on your vehicle or in your trunk.
 
Messages
19,528
Location
Lake Forest, CA
 Originally Posted By: bdcardinal
i always put spares at max inflation. cant count how many i would check and they would be at 0psi.
I agreed. Whenever I check the spare, probably once every 2-3 years, the spare's pressure dropped 15-20 PSI. When I remember to inflate the spare while filling up at gas station, I always had the spare at max pressure on sidewall. The reason I do this is when I need the spare let say a year later, the pressure probably drop some and with pressure gauge in glove-box, I can quickly adjust it down to the level I need.
 
Messages
5,573
Location
earth
i keep a footpump with me so it's no issue to just pump it to normal pressure and forget about it (check one a quarter or so)
 
Messages
14,505
Location
Top of Virginia
I think most donut spares call for 60 PSI. I wouldn't inflate any spare beyond the maximum pressure printed on the sidewall. For most passenger tires, that's 44 PSI. For many light truck (LT) tire sizes, that's 50 PSI and beyond.
 
Top