Tire Pressure Light

ljones · 10-01-2007, 09:12 AM

So this thing has gone off a number of times. i've purchased a number of tire gauges, they all say I'm at the 25lb mark, but that never seems to be enough. Then i have to play run around the car until the damn light goes out. Is 25 lb the actual mark, or is the sticker on my door incorrect. And it never seems to be the tire i think it would be.

Anyone else having this problem? I know my sisters fiance had the same problem in his, but his never went out once it came on.

redhoss · 10-01-2007, 04:46 PM

I just searched this forum and your post was the only one that came up. I have a similar problem and I think I can answer your question. I believe that 25 psi is too low a pressure to run in your tires. My wife's 2007 Touring warning light came on this morning. I checked the tires and they were all right around 25 psi. The door sticker shows 30 psi recommended and I aired them all to 30 psi and the light went out. I want to know what kind of pressure sensor the 2007 Touring has, direct or indirect.

ljones · 10-01-2007, 05:43 PM

Ok, 30 psi is the actual mark. So i went to add more air at the gas station and my tires are at the 30 mark. The light remains on. SO I guess i will just take the car in when i get a chance.

Either the tire pressure gauges i used are wrong, or the mechanism in the car is malfunctioning.

And I always filled them to 30, for whatever reason i was thinking 25, maybe because of the tires on my Olds Cutlass.

phunter1 · 10-02-2007, 02:57 PM

Not sure which 300 you have, but my 300C low tire pressure light comes on at 25 psi. I don't know of any tire that has a recommended tire pressure as low as 25 psi. I run my Goodyear Comfort Treads at 35 psi, warm. The 30 psi on the door is cold tire pressure, after the car has sat overnight. It should be higher if the tires are warm.
Personally, I don't follow the car sticker because the cars can have several different tires on them, depending upon build date and the option package. Instead, I use the tire manufacturers rating on the side of the tire. For example, the max psi rating for my Goodyear's is 44 psi, so 35 psi is well within the tires limits. Higher tire pressure also helps fuel economy, but does impact ride somewhat.

Phil

KWhale · 10-02-2007, 04:22 PM

Quote:

Originally Posted by ljones

Ok, 30 psi is the actual mark. So i went to add more air at the gas station and my tires are at the 30 mark. The light remains on. SO I guess i will just take the car in when i get a chance.

Either the tire pressure gauges i used are wrong, or the mechanism in the car is malfunctioning.

And I always filled them to 30, for whatever reason i was thinking 25, maybe because of the tires on my Olds Cutlass.

This is quite possible ljones. When you check the tires at home, the tires are COLD and show you 25lbs. Then when you drive to the gas station, you heat the tires up and they could be as high as 30lb HOT. The door sticker that says 30lbs, is for COLD tire temps. Also, use the same tire gauge to check the tires at the gas station as you did at home. The garage gauges a severely abused, and often not accurate.

One thing I have noticed on my 300C. 30lbs is too low for me. It was too low with the Conti's, it was too low with the GoodYears, it was too low for the Toyos as well. I say too low as the tires felt mushy, grabbed the crown of the road more and would generally wallow into a corner somewhat. I upped my pressures to 32 or 33 (each type of tire was a bit different) and it made a huge difference. Not so mushy now, runs straighter on crowned roads, and less mushy in the corners. One side benefit of upping the pressure a couple of pounds it better gas mileage as well (less rolling resistance).

I hope this helps you out.

Ethan@Tirerack · 10-03-2007, 02:36 PM

Everything that KWale says is spot on. If you have been running 25psi for some time you may want to have one of your tires dismounted and checked for internal damage. I think you'll be okay but better safe than sorry.

Ethan@Tirerack · 10-03-2007, 03:20 PM

Check and Adjust First Thing In The Morning. Set according to the vehicle manufacturer's cold tire pressure(s) recommended on the vehicle's tire placard or in its owner's manual. This must be done before rising ambient temperatures, the sun's radiant heat or even driving short distances temporarily warms the tires.
Accommodating Variables
Indoor-to-outdoor Temperature Variation. Significant differences between the conditions tire pressures are set (the warmth of an attached garage, heated garage or service shop) and in which the vehicle will be driven (winter's subfreezing temperatures) requires inflating tires 1 psi higher than recommended on the placard for every 10° F difference in temperature between interior and exterior temperatures.
Afternoon Ambient Temperature Increase.* Set 2 psi above vehicle manufacturer's cold inflation recommendations when installing new tires or if the vehicle has been parked in the shade for a few hours.
Tire Heat Generated While Being Driven (or at speeds of less than 45 mph).* - Set 4 psi above vehicle manufacturer's cold inflation recommendations.
Heat Generated While Being Driven Extensively (or at sustained speeds greater than 45 mph).* Set 6 psi above vehicle manufacturer's cold inflation recommendations.
Do Not Release Hot Tire Pressure if any of these variables could be the cause of measured tire pressure exceeding the maximum psi branded on the tire's sidewall by the 2, 4 or 6 psi indicated above for the various conditions. This temporary pressure increase is expected and designed into the tire's capabilities.
*NOTE: Tires on a parked vehicle exposed to direct sunlight will appear overinflated due to the heat absorbed from the radiant energy of the sun. Pressures cannot be accurately set on these tires until all have stabilized in the shade.

ljones · 10-08-2007, 01:01 PM

Ok,so i pushed in more air, and my gauge showed about 33 psi. The light finally went out after i added more air to exceed the 30. Although this took a little trial and error and a few more quarters to see what would happen. I tried to push the tires over 30, the light stayed on. Then i figured I needed to do this tire by tire to see if any specific one was the problem.

So after 2 trips to the gas station, the last tire that made the light go out was the driver side front. I believe only the rear passenger side is at 30. All the others are over, and that front tire is over the most at the 33.

And i went back and checked again, evened out the air in the back tires to be the same, 31. The light stayed out. The front is about 32 on the passenger side.