Here's an interesting observation; you'll recall that I mentioned in an earlier thread that my drivers-side rear tire displayed a slight loss of air pressure - twice over a period of about a month or so - and that some suggested it might be a slow leak cause by a nail, etc.? I can't say what was the cause of it since I still haven't check it, but it hasn't come back since.

Yesterday, on the drive into work, my drivers-side front displayed a loss of about 4 Psi (from 36 to 32) and when I had the chance, topped it back up to 36 Psi. On the drive home last night, now the passenger-side front showed a loss of about 4 Psi.

In full disclosure - and I know I should have - I should be checking all the tire pressures to make sure all had 36 Psi before, or even after, any of this happened, but didn't.

Just thought all of this - a case of rotating musical chairs and a loss of air - a bit odd. Then again, so am I. (Car going in for its annual check-up in 2 weeks, although I will be swapping out my summers for my winter set up).

Best regards,
Jay

 

Fall is the time of year (in N. America) when you usually see dramatic tire pressure fluctuations. It can be 70ºF during the day and near freezing at night. I've seen 4-5 psi pressure fluctuations routinely in all my vehicles over the last several weeks.

 

I was going to add - and not entirely sure if it's germaine to my post - that yesterday was quite cold.

 

I don't remember the easy rule of thumb, but I calculate that dropping the tire temperature by 10 degrees F decreases the pressure by 1.9%. (Tire Rack rounds it up to 2%: http://www.tirerack.com/tires/tirete....jsp?techid=73)


Been meaning to add air to both cars, though it's tricky this time of year with the temperature all over the place.

 

I've had my car for about 5 weeks now, and twice the pressure has dropped to 33/34 in all 4 wheels...just topped back up again at the weekend.

It's getting slightly colder here but nothing dramatic, plus the car is in the garage when not in use. Never noticed this with other cars I've owned before, but then I've never had a car with in-dash display of psi at each wheel so maybe I'm just noticing it more now as a result...

 

My tires are nitrogen filled and as a result I do not experience much temperature / pressure change... or at least as not as much as previously.

One area that I've noticed on my cars over the years is that when I do have an actual slow leak, its often not a puncture, but more often a leak where the tire seats on the rim.. it develops over time and sometimes is only active depending on which part of the tire circumference is on the ground.
Lawrence

 

You're aware our air is mostly nitrogen correct? Nitrogen filled tires are really just a gimmick.

 

+1

And nitrogen expands/contracts at exactly the same rate as air.

 

my tires are hydrogen inflated

 

Oh, the humanity!!!

 

I filled my tires up to 52 psi at a service station this weekend. Had a rather "interesting" drive home afterwards.


52 psi, Pirelli Zero, humid air and 30 F is not a very desirable combination. To say the rear felt loose is an understatment....


But now it is tucked away in the garage and under a quality cover for the winter (which hopefully explains the 52 psi), and I am looking SO MUCH forward to spring :-)

 

Say it isn't so Joe! Whereas I'm looking forward to filling up the passenger front with 4 Psi after I post this and driving into work in about 30-45 minutes. For...lets just say...most of this upcoming winter. Snow, cold, ice be damned! Couldn't stand keeping my F-Type "under wraps" for too long. Under-inflated yes, under wraps no.

 

Sorry to say it is so. It has been below freezing in the mornings for the last two weeks now, and they may put salt on the roads anytime soon, so it's just as good to be prepared (my F-type is not going to be exposed to salt...).


I can also add that I had to pump up the pressure some weeks ago, when the temperature suddenly dropped from an average 64 F to 46 F in less than a week, which resulted in a drop of tire pressure from 38 to 33 PSI.


And when the temperature continued to drop to 30 F, I saw tire pressure drop once again from 38 to 33 PSI.


Hopefully the temperature will not drop below 14 F at any time (I guess the average temp will be ~ 25 F), and that the initial 52 PSI will be enough for safe storage without causing permanently flat spots on the tires over a few months.....


And sometimes when the weather is nice and dry during the winter, I can always take the car outside of the garage (no salt there), let the engine warm up and repark it with the tires in a little different position....

 

Starting an engine just to let it sit and idle is not doing it any favours. Push the car manually if you are worried about flat spots. I'm not aware of them being a problem on modern tires anyway.

 

I believe I've put 40psi in my tires for storage the past two winters, and have had zero issue with flat spots. PZeros the past two years, this is the first year with PSS.

 

I had a set of P-Zeros on my MINI flat spot and never get quite right again after sitting on a frozen concrete floor for a couple months. I don't think the flat spotting issue has been engineered away yet: http://www.tirerack.com/tires/tirete....jsp?techid=42

I have since taken to putting vehicles up on jack stands if they will be sitting for several weeks in freezing weather. It is unlikely my F-Type will be sitting for more than a week at a time this winter. The 4x4s get driven in the crappiest of weather and the others get driven when the roads are clear. I can easily jack up the cars and hit the undercarriage with the pressure washer to rid them of the salt.

 

+1. Unless you're going to drive it (not idle it) long enough to get up to normal operating temp, you're better off not starting it.

Flat-spotting is not a permanent issue with modern tires. As soon as they reach normal operating temperature again, the "flat spots" will disappear.

 

The professionals at TireRack and elsewhere must be wrong, then. 5 Myths about Tires Flat Spots: Caring for your High Performance Car Tires | Race Ramps Blog & Resource Center

 

Which, if you read to the end, promotes a product that will solve Don's 'problem'. Maybe save the whales too.

Funny that the people who promote putting a car on jack stands as a 'cure' never give a thought to what torsional stress that induces on the suspension bushings.

 

Professionals at Tire Rack perhaps, but it's the marketing professionals not the tire professionals. That was a real BS piece.

At one point I had 10 vintage and modern vehicles stored for long periods, because I never had time to drive them all. I've never had a problem with flat spots.