Reference temp for recommended tyre pressure

[Swbimmer]

I am trying to follow the tyre pressure recommended by BMW (which is 2.4 bar). I also know tyres need to be cold. But at what temperature? A month ago my tyres were 18-20C in the morning before being driven and I had them at 2.4 bar. Nowadays they are about 12C in the morning given the change in weather. They have dropped to 2.2 bar.

I can't seem to find the reference temperature at which the tyres need to be at the 2.4 bar. Any advice?

[Swbimmer]

Similarly I have also seen 20C being listed as reference but this was neither from an auto manufacturer nor from tyre manufacturer so I did question the accuracy.

[Swbimmer]

f1nn said:

Road car, driven on the road?

It’ll make sweet FA difference if you set your tyre pressures at 15 or 20 degrees ambient temperature.

Yes normal road car

[Swbimmer]

Ambient, cold and warm I suppose are all relative. Tyres can reach 36C after some (motorway) driving. Cold can mean 23c in the summer and close to zero in the winter... Thus my question on what manufacturers use when they set the recommendation that shows up in your doorjamb

[Swbimmer]

so you are basically saying as we go towards winter and temperatures keep dropping (and thus pressure drops), we need to keep topping up the pressure every so often?

[Swbimmer]

Debaser said:

Yes, as you say, the pressure drops and therefore won’t be correct.

In reality, check them every week or two and you’ll be fine.

Got it!