Winter storage and tire pressure

[Thomas O.]

I have my vettes an 06 and a 73 in storage on a concrete heated floor at 68 degrees and low humidity. I have heard it stated that storing on concrete for four months that the concrete will draw down air pressure in tires. Any fact to this idea? Also, is it a good idea to over inflate a few lbs pressure to prevent development of flat spots? Thanks, tom

[Terry M.]

Re: Winter storage and tire pressure

I'm not a scientist, but I doubt concrete will do anything to tire pressure -- temperature however will.

I don't hear the C6 guys over on CF complaining about flat spots in the spring, and my experience last year showed no flat spots on my 08. What kind of tires are on the 73? I can guarantee you Nylon Cord tires (originals AND reproductions) will flat spot even in a couple of weeks. I thought 73s had radials, but that is one year too new for me. Someone else will have to chime in on that.

[Thomas O.]

Re: Winter storage and tire pressure

Terry: Yes 73's have radials, my 73 has radials which are just 2 yrs. old. To expand on the concrete floor drawing out air there is also the idea that a concrete floor will draw down a battery. Perhaps that is where the idea of draw down of air pressure originated. Thanks for the response, tom

[Terry M.]

Re: Winter storage and tire pressure

That could be where the story came from -- but the concrete and battery story is a myth. Many years ago, when battery cases were made from rubber there was a grain of truth to it -- if the battery case was dirty. Automotive battery cases have been made from plastic since the early 1970s. A battery will still deteriorate more rapidly with a dirty case, but this will happen regardless of the kind of surface it is stored on.

BTW: At the turn of the last century (late 1800), when electricity and the automobile were in their infancy, most electric power to the end user was Direct Current. In urban areas there were large fleets of electric trucks used to deliver milk, coal, and dry goods to residences. These vehicles returned to their garages at night and were recharged over night. The utilities used large (10-12 feet high) storage cells to store electricity during the daytime low-use period and discharged these cells in the early evening when there was high demand. These cells had cases made from wood and rested on stones set in concrete. So much for that myth.

[Tim S.]

Re: Winter storage and tire pressure

Thomas,
Personally, I would not worry about it. Yes, the radials are going to stand up better to the flat spotting. IMO, I believe the proper tire pressure at storage time would be fine. If you have a problem with them bleeding down, your problem is not the concrete. To take the discussion on step further, a person can inflate the tires with nitrogen rather than shop air.
Nitrogen does not bleed off (molecular structure as compared to air) and does not fluctuate in pressure as much as air when temprature is factored in. Higher end tire shops have nitrogen equipment. Obvoiusly, this can be inconvienent to top off or maintain tire pressure. Hope this helps.
Tim

[Duke W.]

Re: Winter storage and tire pressure

Nitrogen is a myth. See archives.

Inflate the tires to the maximum cold pressure placarded on the sidewall or at least 35 psi.

TP drops about one psi for every ten degree drop in temperature and vice versa. At constant temperature if the TP drops more than 2 psi per month there is a leak.

Oxygen, nitrogen, water vapor, and the other gases in air all behave as ideal gases to less than one percent deviation. The issue is condensation of water vapor if temperture drops below the dew point.

Air tires at low relative humidity. If tire temperature drops below the dew point of the installed air, TP will drop due to water condensation.

Commercial nitrogen is dry enough that this will not happen, but you can prevent it by airing the tires at low relative humidity and having a dryer on the compressor system.

The molecule size story is a myth.

Duke

[Wayne K.]

Re: Winter storage and tire pressure

I've found that different tires react differently to setting in one spot for a long period of time. To be safe I always raise the pressure in my stored vehicles to 45 lbs. if stored in a heated environment and 50 lbs. if stored in a cold garage ( freezing and below ). Also rolling the car a foot once a month will work if you don't want to air them up. I don't think it matters if the car sits on concrete or wood or whatever. Another myth I've heard is if you sit on a concrete floor too long you could get piles.

Wayne