[aftcargoheat]

Took delivery of new M3 G80 competition in the UK four weeks ago, and have done the 1200 mile (2000km) run-in service now. Previous car was a F90 M5 and, to my feel, the M3 was far too nervous and 'frisky' - even sitting at 70mph on a good tarmac it didn't care where it steered. I mentioned this to the dealership when I had the service done, and they said they could find nothing obvious but they had reduced the tyre pressures by about 3 psi.

I am amazed how much difference in feel this has made. So when cold (ambient 12 degrees C, (54F) they are now 31 psi, and when I get the tyres up to about 29 degrees C, (84F) they are reading 34 psi.

Before, when hot, they were up at 38 psi and were already at 34 psi sitting on my cold driveway.

I wonder if anyone else has had similar effects and has been surprised quite how much difference this small change in the tyre pressures make? The car is now much more pleasurable to drive on a normal commute.

Looking at the tyre pressure recommended settings data inside the door pillar, it seems to me these recommendations should say 'when hot'.

[turbojg]

I'm guessing it has to do with the height of the sidewall. I think though that maybe BMW feels that the "when hot" is understood as in any performance situation such as racing or using 'launch control' it is stated that the tires be warmed up.

[Needsdecaf]

Pressure is always measured when cold.

Yes, cars with low profile tires are very sensitive to tire pressure changes. I always find that the manufacturers recommendations are pretty harsh, and run my tires lower. Usually at or a bit below the comfort setting, especially since I don't really need to worry about the >250 kph / 155 mph warning above. LOL.

I've done this for years on multiple cars including both my 911's and never had abnormal tire wear or degredated handling.

[davidmct-M3]

I adjust the cold pressure to spec anytime there are significant temp or altitude changes. If I was on track I would adjust warm tyres to spec. When drifting tyre pressures really affect handling if too high/low.

[pdx]

wait until you start checking the My BMW app and the Recommended pressures change on you every time you drive your car. better to look at the door pillar suggestions and forget it?

at the same time, i do adore my AVID pump, which makes sure the pressures are exact and then turns off. i wish i had one of these when i first started driving.

[aftcargoheat]

Yeah, I agree with everyone. I know placarded pressures are always 'ambient cold' settings, but it does seem the M3 competition with a light load (only one occupant) might need to be back at 31 psi, maybe 2 or 3 lower than 'door pillar' placard.

Thanks all for engaging on this.