[psp888]

Recommended normal tyre pressures for my car are 2.2bar front and 2.4bar back.

On the morning commute to work startup, iDrive shows pressures are 2.1 front, 2.3 back. After 10 minutes of driving they rise to 2.2f/2.4b and after 30 minutes they could go up to 2.3f/2.5b.

On the drive back home, pressures are already showing 2.3f/2.4b, and by the time I get home they show 2.4f/2.6b.

Is this ok? are they over inflated? Will I get uneven tyre wear?

Any advice would be helpful. Thanks

[HighlandPete]

Originally Posted by psp888

Recommended normal tyre pressures for my car are 2.2bar front and 2.4bar back.

On the morning commute to work startup, iDrive shows pressures are 2.1 front, 2.3 back. After 10 minutes of driving they rise to 2.2f/2.4b and after 30 minutes they could go up to 2.3f/2.5b.

On the drive back home, pressures are already showing 2.3f/2.4b, and by the time I get home they show 2.4f/2.6b.

Is this ok? are they over inflated? Will I get uneven tyre wear?

Any advice would be helpful. Thanks

Reading tyre pressures is fine, but easy to get too anxious, as pressures are changing all the time according to use. Ignorance can be bliss.

What you are seeing is totally normal. 0.2bar increase, well inside the working tolerance.

Remember it is the setting pressures on the door shut placard, not working pressure. We expect increased pressures, allowance is built in with the setting values. If not, we'd get odd wear running all day at the setting pressure.

It is one reason I run RFTs at higher setting pressures. I make lots of 12 mile trips, often in the wet, where tyres don't warm much and pressures never get to the ideal working pressure. To prevent odd wear, particularly on the shoulders.

[planemad]

Air in the tyre expands when warm and contracts when cold.

When the air expands the pressure goes up and vice versa.

[dopper99]

Because your tyre pressures increase when you're driving, this is why you should NEVER check and top up your tyres at a garage.

Do them on your drive with the tyres cold.

[simon.]

Originally Posted by dopper99

Because your tyre pressures increase when you're driving, this is why you should NEVER check and top up your tyres at a garage.

Do them on your drive with the tyres cold.

This. Check & adjust when cold to recommended pressures & leave. The only time I do hot is on track when reducing them for grip.

[teaston]

Yes it's fine.

Recommended pressures are at ambient temps, so if most days are currently 14°C, fill them when they're at 14°C to the recommended pressures.

[psp888]

great, thanks for the advice

[hudson012003]

Originally Posted by psp888

Recommended normal tyre pressures for my car are 2.2bar front and 2.4bar back.

On the morning commute to work startup, iDrive shows pressures are 2.1 front, 2.3 back. After 10 minutes of driving they rise to 2.2f/2.4b and after 30 minutes they could go up to 2.3f/2.5b.

On the drive back home, pressures are already showing 2.3f/2.4b, and by the time I get home they show 2.4f/2.6b.

Is this ok? are they over inflated? Will I get uneven tyre wear?

Any advice would be helpful. Thanks

I was told to look at ATS nitrogen replacement by a colleague. Early days & not sure if it will pay off but after checking pressures (cold) over last couple of weeks it's all good....

[teaston]

Originally Posted by hudson012003

I was told to look at ATS nitrogen replacement by a colleague. Early days & not sure if it will pay off but after checking pressures (cold) over last couple of weeks it's all good....

Fifth gear did a test on this before, said it made no difference on a road car!

[DriveS]

One of the Gas laws. If the volume is constant then pressure will change in proportion to temperature. However its not quite true with tyres as they are made from rubber which changes its hardness and volume with temperature. I recall the pressure will change in a tyre about 2Psi for every 10degC change in temp.
This is why in some parts of the world where the temps can change massively in a day or two, tyre pressures should be adjusted.

Also never check and adjust tyre pressure when the tyre in the sunlight.

I keep one of these in the boot. Great little pump.

https://www.amazon.co.uk/P-I-Auto-St.../dp/B00WOT3YM6

[Trialskings]

(P1V1)/T1 = (P2V2)/T2

...I think

[DriveS]

Originally Posted by Trialskings

(P1V1)/T1 = (P2V2)/T2

...I think

Yeah that's right.