MCVetteLs6

2 weeks back weather started to get better. upper 60's- lower 70's. even a couple of days near 80..

so i went to get an oil change.. also had them put in a little air in the tires..
cold 30 psi
warmed up about 34-35 psi

at the begining of this week we had a small cold front.. little rain, not to bad...

this morning i start the car up.. at tires measure 25-27 psi? and after warmed up on the highway barely got 30 psi?

its no colder today than it was the days when it was reading 30 cold..
new tpms? i dont know..

thank you

Matt

tomringo

Are those readings the actual pressure taken with a guage check of each tire or off your DIC? Results can mean something different depending. Not sure if you did, but should check with a tire guage and then cross check agaisnt your DIC reading. A nice digital TG is good to have. Just a thought.

MCVetteLs6

thank you for the responce,
yes i have a digital. and i did cross check it. the digital was exactly 1 psi higher all the way around compared to the DIC no matter if it was cold or warmed up!

Jewjenk

The garage pumped in warm air, then when the temp dropped, the air condensed, resulting in low pressure. Had that happen to me, car in warm garage, drove it out in 20 degree weather. All four tires needed topping off. Maybe this is the reason.....
Top them off and see if it happens again. Does not seem natural that all four sensors would go at once..........

rebelheart

Sounds like normal temp differential to me.

MCVetteLs6

i didnt think it was normal to me either.

i just found it weird that after i topped them off.. a week later even with the small amount of cold we had for a day or two, it would drop them all that dramaticly..

johnson-rod

According to Tire Rack's website, tire pressures drop 1 lb per 10 degrees drop in temp.

MCVetteLs6

hmm. well ok but my tire pressured drop.. give or take 4-5 psi over night, after 2 days or small cold and little rain..

by tire rack, that means it would had to have been 40-50 degress colder.. which it wasnt . 10-15 MAX.

but still, ok i understand it got colder and tire PSI droped.. but it got warmer now, and was only cold for a couple of days.. and my PSi is permanantly down by 4-5 PSI?

i who nows.. ill just re fill them. Bleh..

summer hurry the hell up

paviesVette

Keep in mind your garage floor is going to be cooler then ambient, and your tires are going to be hotter then ambient when you get home from a hot drive. There is a greater shift in total temperature then just the monitored outside weather temperature. I've seen my tps sensors fluctuate 5-6 psi overnight depending daytime temps.

vette.mix

hmmmm........ today is 4/1

99 vett babycar

Did YOU check the tire pressure with YOUR gauge when the car was worked on ?
Its one thing to tell them 30psi, its another for them to actually do it right. In most cases tire shops have air nozzles that can be set to a given psi but, also in most cases, over a period of time, the calibration of the setting goes off - so "30 psi" becomes 28 psi all around.
The odds of all 4 tires losing the same pressure over that short a period of time are astronomical.

jrose7004

Temps in your tire certainly varies with hot or cold temporatures, mine certainly do.

Oldvetter

Also, don't forget tires will heat up 4-5 psi from driving. That COMBINED with temperature drop and you have your psi difference. ALSO GOOD POINT ON TEMPERATURE OF GARAGE FLOOR.

Dark-Knight

That's why I replaced the air with nitrogen... ...crazy that I am.