Hi so im new to jeeps, i have owned mine for like two months and decided to get bigger tires. I went from the stock size to a 33x12.5x17 i got the tires in good shape used from a buddy, but i took my spare off because it didnt look right have bigs tires and the tiny spare...i drove around most of the day, but then tonight my tire pressure light (!) came on. Why is this? can i reset it? the tire pressure is around 37 to 40 psi on the tires but i set/checked these pressure mid day so now that its cooler out idk if that affects anything?
THanks

 

10 degrees of temp = 1 psi. Your tire pressure should be measured cold. Meaning no driving temp and average morning temps for the season. The spare shouldn't matter because the way I understand it the computer only reads a spinning tire. I know I need mine at least up to 34 or the light comes on. Once you are over it's setting and drive for a couple minutes it should clear. There are aftermarket programmers like ProCal that allow you to change what pressure activates your low light. If you want to run your tires below stock recommendation you just set it below what you want or you can set it to zero and it will stay off. From the factory it is set to just below what is on the driver door sticker.

 

Did you get new wheels in addition to the new tires?

 

yes the wheel came already on the tires all i did was take them off my buddies jk and stick them on mine!

 

how do i zero the system? so the light just wont come on? but does zeroing the system mess other settings up?

 

idk if it help to see the tire? the rims and tire are new to my car i was running a stock tire with like 15's or 16's idk whatever they are

 

Your Jeep has a Tire Pressure Monitoring System (TPMS) that does exactly that, monitors the tire pressure. With the different wheels on your Jeep I would bet that the transmitters (sensors) in the wheels are not communicating with the Jeep's system.

If that is the case, I believe a good tire shop (or the Jeep dealer) can reset the system to allow the sensors in the wheel communicate with the Jeep.

BTW, under the Owners tab on the Jeep website, Owner manuals are available for download on 2004 through 2012 model Jeeps.

 

With a ProCal programmer from AEV or another after market programmer you can take it to zero and it will ignore a low tire or the absence of tmps.

 

is it possible your friend was running without tpms sensors in the wheels? you might want to ask him
i would get a programmer none the less to adjust your speedo (tire size) and for future mods

 

yes he has a 2007 and didnt have the sensors i guess! ill just take them to a tire place and have them reset!