For those with more experience, how long does it take for the air pressure to drop down in the HCH. Had not checked mine for a month or so and they were down 5 lbs or so all the way around, but too, it is cooler now. Dont find many cars these days that air dont go down over time.

 

That's a tough answer as your valve core, valve stem could have a super tiny leak. I've gone for 4 months without losing pressure, then 3 weeks later they are down 5 lbs.

 

Oxygen leaks right through rubber, so over time you'll lose some pressure due to that phenomenon.

 

Some of my tires go for months without loosing much, some are faster.

I've picked up a nail or somthing in one of my tires, and I visually check this tire everyday, and gauge-check every 3rd. I have to add about every 4th-5th day.

I'd have it fixed (Plugged) but I'm close to my 50K maintenance and the dealer will likely replace the tires at that time.
I've got one of those free tires for life deals.

All 4 tires are gauge checked at least once a week.

 

I keep my pressure pretty high - 49# - and I usually only check/fill every 3 weeks or so. In that time I'll see a drop of maybe 3 pounds but nothing drastic, sometimes no change at all.

 

On my HCH, I keep the pressure at 44 psi all around. I find that the pressure stays nicely for several weeks, but as soon as a strong weather system passes through, I lose pressure. For example, I checked the air pressure two weeks ago, 44 all around. Yesterday I checked again (after the fierce rain and wind storms) and the pressure was down to 40. The temperature was 20 degrees cooler than two weeks ago (that would account for 2 psi).

So, my belief is that there are many factors that could cause variance in the pressure. One should check air pressure more frequently than once a month, depending on use. For my 700 miles per week, at least one a week is probably a good idea. Now, putting that idea into practice...

 

Mine on my 03 HCH have held pressure nicely. I check them every 2 months or so, and rarely have any significant issues. It's been said in other threads that 10 degrees temperature change will cause 1 psi difference. That, coupled with a 1-2 psi natural loss over 4-5 weeks may explain your situation.