i was wondering if it was normal to have the TPMS light show up randomly. this morning i turned on the car and the light showed up, and when checking all the tires my left rear tire showed a buldge on the sidewall where the tire meets the road. but my question is, is this normal? this is not the first time this has happened to me where a tire just randomly lost pressure. a month or so ago i had my right rear tire loose pressure and it looked kind of flat but all i did was put air in it and it was good to go... until now. my question is if this is normal for a stock tire to do this randomly

 

My light turned on the other morning too. Checked the pressure in my tires, added some air and all was good.

This is only the second time I have had to do it in over a year and my tires are stock.

 

Unless you are talking of a timespan of 3 months between filling it up and it getting saggy, it's not normal. I believe tires lose 1 PSI per month, and the TPMS cuts in at about 28 PSI or so.

*edit* the only reason why your TPMS would come on in the morning and nothing is wrong is if your tires are on the lower end of filled (29PSI) and it's a cold morning.

 

hmmm, well im talking about over night [kind of thing], maybe i ran over something but i could not find a [leak] yet. it must be pretty small because it was a bit saggy, not completely flat yet. i just filled it up with air and drove 33 miles to get to school [class right now] and the light still did not show up.

the thing is that this has happened before, just not from the same tire, yet the other tire is still fine.

 

do you have aftermarket MP3 (e.g., XcarLink) installed?

 

nope... but the TPMS was in reference to the previous time this has happened
but today the tire seemed kind of bulgy at the bottom, i just dont see how that can happen over night! i inflated it and it seems to be holding up now.

 

it was probably towards the low end 29 like said above and a cold morning came on....remember rubber is porous and air molecules can fit through the pores so it is going to leak...that why you are suspposed to check your pressure often

 

well i finally had time to check the tire and it turns out i ran over a screw [but that still doesnt explain why it happened to the other tire a couple months back... but i guess 04RX8man is right about that one