My mileage dropped and I found out why; my tires were underinflated by 15lbs. Now that they're back up to 44, which is what the tire says to use, I can already see my mileage climb back to where it was previously around 19mpg.

 

below freezing makes the low tire light come on

 

I've noticed extreem cold robbs my tire pressure a bit....however 44 is a bit high ....what tires are you running?? I've read on here several times that 28-32 PSI is about average.....

 

A drop in pressure is definately common when the tempurature gets cold. But such a large drop as you have seems excessive. As already stated, 44PSI is quite high.

 

You should seriously look into putting nitrogen in your tires. Nitrogen filled tires are not as affected by air temperature fluctuation like compressed air is. Also, as a compressed air filled tire loses approximately 1-3 psi a month, a nitrogen filled tire may lose 2-5 psi a year. Nitrogen works best in a new / newer tire. Unfortunately, on older tires this isn't the best fix, but when you buy new tires, DEFINATELY get nitrogen in them instead of compressed air.

 

Yes, however if you offroad, you generally want to air down your tires. Nitrogen and Oxygen does not mix, so it would be a waste of the $30 to do the nitro.

 

Yes you're right actually.35 psi is what's required. Still though mine was off by 5psi and that'll make a difference.

 

No

My tires are 35 psi at 20 Celsius

At minus 35 Celsius, the light doesn't come on

 

Actually they mix quite well, you breathe the mixture on a daily basis.

For the other poster, Nitrogen will leak just as fast as CO2 or air. Gas density does not vary that much.

I have pure Nitrogen in my tires only because it came that way from the dealer. Well not all of my tires, I've had a flat and had to refill and each time you air down and refil with compressed air the mixture gets closer to the air we breath.

Nitrogen in tires reduces heat content at high speed, keeps the pressure more stable between high and low altitude, and doesn't oxidize the inside of the tire as quickly due to the lack of Oxygen,

Now I have that cute little Nitrogen sticker on my doors, and on my fancy valve stem caps which is sure to confuse the Nimrod out in the sticks when he goes to top off my tires. LOL. This is not to knock the use of Nitrogen, but to point out that the time & place for it is not in a Jeep unless you want to carry around a nitrogen bottle and regulator.

Edit: the only way to get pure Nitrogen in your tires is to mount the tires, pull a vacuum on each wheel without breaking the beads then refilling the tire with Nitrogen. Anyone tells you that they fill and dump two to three times before the final fill is self deluded or a pure liar. It would be impossible to do with pulling a vacuum.