I think it was about a month ago when I posted that I had lost some tire pressure in all tires. Well I just checked them again today and all 4 tires were down between 3 to 5 pounds.

Anyone else?

Thanks Russ

__________________

Yes, Russ, this has happened to me too. I'll be checking my tires cold tomorrow morning; it's been about two weeks since I filled them and they were slightly off then. I don't think it's right, but I expect this to be the norm.

I will report.

Snaxster

__________________

2008 Boxster Black/Black/Sand Beige, 6-speed, PASM, 18" Boxster S wheels, Preferred Package Plus,
Sport Steering Wheel, Automatic Climate Control, Windstop, Hardtop, Porsche rubber floor mats,
deleted model designation, clear side markers, 3M clear bra, set of winter tires and wheels.

Unless you have weather conditions that never change you will have changes in your tire pressure. Mine change with the temp and pressure with predicatable accuracy. However a five pound drop is pretty unusual and a consistent reduction in pressure is weird. Do you still have those non-standard valve caps? If so ditch them. Also make sure you have a reliable guage. Intercomp is my new favorite based on Brad's recommendation and my trial. I'd start checking them daily to see if I could figure this out.

I recant. A loss of 3 to 5 pounds did NOT happen on my CS.

That said, I guess I wish the tires' pressures would stay more stable than they do. But as Santa Fe said, perhaps the fluctuations I'm seeing are normal.

Please let us know what you find.

Snaxster

__________________

2008 Boxster Black/Black/Sand Beige, 6-speed, PASM, 18" Boxster S wheels, Preferred Package Plus,
Sport Steering Wheel, Automatic Climate Control, Windstop, Hardtop, Porsche rubber floor mats,
deleted model designation, clear side markers, 3M clear bra, set of winter tires and wheels.

Russ - Some of the variation, as SF says can be due to the changes in temperature. It will depend what the tepmerature was and were tires stone cold, or did you drive the car to the gas station when you last checked/filled them? Or did you last check them in the sun on a sunny day? All these things can make a difference. 2-3# difference is pretty common, 5# is on the edge of "what the heck" territory. Try to check them cold before the car has moved, in about the same temperature conditions if you can maybe every other day for a week and that should give a feel for whether or not they're "leakers." All tires lose some air over time, but the chance that all of them would be "leakers" around the rims is pretty remote. Also get a gauge you can really trust.

brad

Ever since you first posted this, I have been careful to always check the pressure every time I get gas.

Now in Hawaii, I am expecting that you have little temp variations but here, well like yesterday it was 70 degrees and today 40.

As others have said, the tires must be cold. I drive just about a mile and a half to the gas station check them, and they have changed little, maybe a pound or so across the board. As the weather has gotten colder, the rears seem to stay close to the same. Fronts down maybe a pound but I'm guessing its the weather.

I'm going to figure that the manual got it right. Check the pressure everytime you get guess but its very important to check cold. I checked my rears and they were UP 2 pounds but then realized I had been driving

Out of curiosity does anyone here have TPMS? If so, do you bother using it?

__________________
****************
2006 Cayman S
Carrara White
semi-loaded
****************

Yes, it's standard on all '07 Caymans. It's very useful in determining if a tire has a pressure discrepency from "normal". I do not believe that TPMS is accurate in terms of the pressure it displays but my concern is that they are the same side to side (that's why I use "normal" as a reference). I use an Accutire gauge and TPMS shows about 2 lbs. less compared to my gauge and I just mentally adjust for the difference.

While I drive I can see the pressure of the tires "real time" as they rise when heating up after some use.

__________________
Tracy
San Jose, CA
2007 Cayman S
Artic Silver/Black

Thanks All,

The rears lost almost 5 pounds while the fronts were closer to 3. I will admit it was much cooler today when I checked them. I do have a good digital gauge. I will check them again in a week and see what gives? I did take my car in for servicing and thought maybe they let some air out? They did replace a broken valve cap.

SF, I did take off those metal emblem valve caps and put the standard plastic ones back.

Thanks again,
Russ

__________________

Wait! That might be the problem

What size wheels you got? Stock 18 or 19?

If its stock 18, then NM.

If you got 19s, that is the problem

When I bought the car, I told the dealer "make sure the tire pressures are correct"

After reading your first thread, I checked and they were low, all around, ~4 pounds. I fixed that. Went back to the dealer for something minor, told them to check the tire pressures. Got the car back, checked a week later ... All low ... ~4 pounds

Fixed it again. A month went by, weather about the same temps, no change

Checked a week ago, down about about 2 pounds but its also 29 degrees here this morning. Thats OK.

I had figured out and am convinced it was the dealer. I am willing to bet they just put in whatever the stock pressure is for the 18s. The 19s have more pressure and I bet they were letting air OUT! ... At least that is my hypothesis.

A few years back I took our SUV to Jiffy Lube, and all the tires looked low. Checked them and all low 5 pounds all around. I think they put 32 pounds into everything but in this case they put 27 pounds in all the tires Filled them back to normal and they were never low like that again.

If you got 19s, I am betting on the dealer
If you got 18s, Well I tried

Here in Wyoming, we see bigger temperature swings than HI, so I've grown accustomed to seeing 4-5 (or more) psi swings that normalize once the tires are warm. We had a 72 degree drop last week with the arctic air mass that's entertaining the rest of the country now. I would say you're just observing normal physics, though there may be a sensor error component related to temperature change, I suppose. I believe the sensors take temperature into account when calculating the delta from normal. If all 4 sensors are behaving similarly, I wouldn't get too excited.

Andy