[Woody_91]

Hey Guys,

This is my first BMW and first winter with it as well so forgive me if I'm being thick.

Last night got down to -8 and when I went out earlier today, after driving for about 30 seconds car pop-ups with a warning about tyre pressure being low, thinking I had another puncture I pulled over and checked the computer, where it says all 4 tyre pressures are low. I know pressures are lower when tyres are cold but they were reading 1.6 or 1.7 all round and triggered the warning. After driving for about 10 minutes they started to come up slowly (5 mile journey each way separated by a couple of hours) and on way home they were up to 2.0 so at least I know I haven't got punctures in all 4 tyres.

First thought was to head to petrol station to check PSI and put some air in if needed but I thought if I increase the pressure so it's normal when they are cold, once tyres are warmed up will they not be then massively over inflated? At the same time I don't want to drive around with low pressures and damage the tyres.

Just wondered if this is normal or not and if there was anything I needed to do with pressures in winter. Given BMW are sold in countries a lot colder than UK it seemed a bit strange that a warning like that would be on all the time during winter.

Again sorry if I'm being thick but have a drive down south again in a few days and don't want to be sitting on the motorway with pressure warnings.

[teaston]

More likely that the pressure sensors are crap when they're cold.

Still best to check with a guage, recommended pressures are at ambient temperature, so when the outside temperature is lower they need more air put in, just remember to let some air out in spring time.

[Woody_91]

Thanks for that, did cross my mind as it seemed unlikely all 4 tyres would lose so much pressure over night.

What do you run your tyres at during winter time? if you run non winter tyres that is.

Thanks for the help

[teaston]

Originally Posted by Woody_91

Thanks for that, did cross my mind as it seemed unlikely all 4 tyres would lose so much pressure over night.

What do you run your tyres at during winter time? if you run non winter tyres that is.

Thanks for the help

Just pump them up to the recommended pressures on the door sticker when the car hasn't been driven for a while

[Norris-wf]

I had the exact same issue. Happened after one of the very cold nights and got the warning too. I do need to measure them also to compare what them to the sensors. It's currently saying 33psi in the rear and 32 in the front of it helps you which is a bit under the recommended.

[savgeax]

My friends new mini has the same issue at the moment. I would not worry... abit like F1, when tyres warm up the PSI increase. It's just very cold at the moment.

[sensible]

Tyre pressures will vary massively from winter to summer as the air expands in the summer and contracts in the winter , that is why you need to check them regularly. Put the correct pressure in when the tyre is cold. They will increase as the tyres warm up but the pressures quoted are cold tyre pressures.

[Jon D]

Originally Posted by sensible

Put the correct pressure in when the tyre is cold. They will increase as the tyres warm up but the pressures quoted are cold tyre pressures.

This is correct; always check pressures at ambient temperature (not after driving) and the system will allow for pressure increase as the temperature rises with rolling friction.

[Woody_91]

Thanks for the info guys, ill check later today to see if they are actually down or if it's a sensor issue.

Can never be too careful when it comes to tyres can you.

[stefan4]

theres so little air in these tyres that fluctuations in ambient temperature can have quite an effect on the pressure. Regular checks with a guage a correct accordingly is the best way to keep the pressures at optimal, this applies to Summer aswell for the opposite reason