Tire Pressure Monitor alarm / warning

[alrats1971]

In California here, freaking freezing cold the past few days, coldest days of the year. I just bought my 2009 BRG Mini S last month (Nov 8th) with Run-Flat Tires. This morning I started my car and first got a snowflake warning indicator, then immediately after that I got a Low Tire! warning indicator (the small warning light (!) came on in yellow in the large spedometer area, then the same warning indicator came on with the words "Low Tire!" in red in the tachometer area).

I looked up the snowflake & was relieved to find out it was just warning me that it's freezing outside (duh!) & to be careful driving & beware of black ice, etc.

However, looking up the other light, I found out this more than likely means at least one of my tires is low. I left the car at home & didn't drive it. I checked the tire pressure in all four tires, and found that three of them are around 32 to 35 psi or so, but the front passenger tire is below 30 -- looked to be about 26 to 28 psi. I didn't see any damage to the tire or a nail or anything, but I'm really not an expert at that. I figure I'll check the tire pressure again in the morning and see if it is the same or if it is even less.

Two questions about this:
1. Could the extremely cold weather be the cause of this much tire pressure loss in one of the tires, or is this likely something that is actually wrong with the tire?
2. What is the desired psi to keep these tires at? The tires say 51 psi Max Pressure, but I know that can't be the actual proper tire pressure. I can't find the spot on the driver's side door where it is supposed to be labeled.

I will call the service dept at the dealership to see what they say, but I'd also like to find out what other owners have to say about it. Any help is appreciated. Thanks!

[ran-o-matic]

Extreme cold? How cold is that where you live? Low temperatures do result in lower tire pressure and often air must be added to compensate. In addition, changing temperatures can allow air to leak out when the tire/wheel combination expands and contracts.

Between 33/38 psi for 16" tires and 38/41 psi for 17" and 18" tires is specified with the higher number for heavy loads plus speeds in excess for 100mph. Look in your manual to make sure - there is a tire pressure table. Many people experiment with tire pressure to alter handling and fuel economy.

Remember to check tire pressure when the tires are cold.

[pilotart]

If your tire pressure sticker is missing from your driver's door jamb, your Dealer should be able to replace it.

A large temperature drop could account for several pounds of pressure loss in all tires and set off your TPM (think it will respond to a 3 pound drop).

The additional loss on your passenger front tire would be something beyond temperature and would be more than enough to trip the warning by itself.

It could be a small 'puncture' in that tire that only leaks when that tire is parked in a certain orientation, but should be repaired anyway.

Especially with 'Run-Flat' tires; the TPMS system is needed to provide warning for a 'low' tyre that could be damaged by running at a pressure that would not be obvious by 'look' or 'kick', also just a couple pound difference could affect your braking and handling adversely.

[MissWeava]

Alrats -- I'm in Los Angeles where it has been unusually cold too. Same story - new Clubman S in August. This morning I had the yellow low tire light and the red light in the tachometer, just like you. My tires are 17" run flat tires and the pressure is between 32 and 35 on all four of them. I see it should be between 38 and 41. Dealer is a long schlep away so I'm trying to find out whether I can just go and top off these run-flat tires at the gas station and re-set the lights and see what happens? Presumably the light will come back on again if there's still a problem, in which case I can make the trek to the dealer. Is this a sound approach? I'm not very savvy about cars so I'd appreciate any input.

[IanT]

I have a UK car on 17inch run flats Bridgestone Potenzas which quote tyre pressures of 2.4 bar which roughly converts to 35psi. As others have said it is important to correctly inflate the tyres, particualrly with run flats which have very hard sidewalls and a fairly stiff ride. If they are too hard the car will bounce around corners and be thrown off course, aside from unnecesary and expensive tyre wear. My car was delivered with overinflated tyres and by reducing to the correct pressures it impoved the handling. The big issue though in your case is the stark difference in pressures which will cause dangerous handling problems. I check mine weekly and top up with a foot pump as I don't really trust garage air lines.

[alrats1971]

It doesn't normally get that cold here, but, yes, it was below 32 degrees earlier this week - unusually cold for here. I was told by the dealer to just fill it up with air & reset the monitor, and keep an eye on it, check it frequently to see if it goes back down & how quickly. So that's what I'll do today. I just bought this car a month ago, and it seems to me that if this tire has a leak this quickly but hasn't been damaged, they should just replace it. ARGGH!!!

[Sejanus]

I really don't think it can be the temp. As much as we Californians may have been complaining about the cold lately, it just wasn't all that cold by anyone else north of the tropics standards. The only time mine went off like that there was indeed damage to the tire.

[IanT]

May be a silly question but had you ever checked the tyre that was underinflated (as you say the car was new)? It may have been delivered underinflated and the cold snap took a few pounds of pressure out which triggered the alarm. Alternatively there could have been a small amount of dirt in the valve which allowed a slow deflation. You could try putting some air in and then releasing some of it to blow out any dirt and then re-inflate to correct pressure so that you were sure the valve was seating properly. If it is still a problem and there is no obvious damage I would take it back and ask for a new tyre.

[pilotart]

Quote:

"...found that three of them are around 32 to 35 psi or so, but the front passenger tire is below 30 -- looked to be about 26 to 28 psi. ..."

Nothing to do with temperature change, but TPMS should alert to this condition.

Depending where the leak is, it most likely could be repaired, but might need replaced.

[alrats1971]

Quote: Originally Posted by IanT (original)

May be a silly question but had you ever checked the tyre that was underinflated (as you say the car was new)? It may have been delivered underinflated and the cold snap took a few pounds of pressure out which triggered the alarm. Alternatively there could have been a small amount of dirt in the valve which allowed a slow deflation. You could try putting some air in and then releasing some of it to blow out any dirt and then re-inflate to correct pressure so that you were sure the valve was seating properly. If it is still a problem and there is no obvious damage I would take it back and ask for a new tyre.

This is what I was wondering, too. It didn't even occur to me to check anything on the car the day I got it, since I bought it new from the dealer. You'd think they would have checked everything before having it leave the lot, but maybe not. Or maybe it is a slow leak & just took a month to get down that far. I've got it back up to 33 again & will check it every couple of days, so we'll see how it goes.

Oh, AND, I found the label on the door frame. I was totally looking in obscure places thinking it would be a small hidden thing, and didn't even think to check the most obvious spot. Can't believe I didn't notice it, it sticks out like a sore thumb!