21” wheel tyre pressure

Wheels, Tyres, Suspension, Chassis, Issues and Fixes
Am89
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Post by Am89 »

My turbo runs 21” wheels with Michelin tyres. I run the recommend 2.3 bar front and 2.5 rear pressure, as it’s usually just me in the car. I check pressure once a week and monitor the TMP. I’ve noticed the front tyres, esp the front drivers side looks low on air.. the pressures are all correct. Should I run more on the front maybe? My mother in laws 2020 Macan runs the same wheels and tyres - albeit in N2 and hers look fine. My tyres are N0

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Rab J
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Post by Rab J »

Sometimes different makes of tyre can look different on a car even if the same size and presure.
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SAC1
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Post by SAC1 »

Provided that your t.p. gauge is calibrated correctly and you do the check when the tyres are cold, then stay with the PORSCHE recommended pressures for normal load for your use. Do not rely on the TPM. N0 and N2 makes no difference pressure wise. Even if your tyres were worn out [2mm] and your m-i-l's Macan tyres were brand new [8mm] - this would not be visible as your described "low"

Are the Michelins on both cars exactly the same pattern?

Does the door sticker for pressures state 2.3 bar front and 2.5 bar rear on both Macans? I ask because when we moved from a 2014 Leon to a 2019 Leon FR on exactly the same 18" wheel and tyre size, the pressures for the new one are 0.4 bar higher all round. This is as a result of WLTP to give lower rolling resistance / lower CO2. Now a heady 2.9 bar front and 2.6 bar rear.
Steve

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Am89
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Post by Am89 »

Pressures are always checked and adjusted when the cars been parked over night. And the tyre inflation machine and TPM always match.. not sure about the sticker marking inside her 2020 Macan but I’ll check when I’m over next. Not sure about tread pattern but both are latitude sport 3 - N2 and N0 - mines being the latter. Both new tyres as well. My old Pirelli’s didn’t look low on pressure or maybe I didn’t pay attention.. I’ve monitored the pressure and no loss in any of my tyres over the past 7 days and 150 miles.
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Tom 2000
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Post by Tom 2000 »

The recommendation of tyre pressure is at 20 degrees so you could actually be over inflated. Use the on screen display for fill required rather than the live pressure display. Use of live pressure display is expressly warned against.
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Am89
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Post by Am89 »

To confirm, is it 2.3 / 2.5 if vehicle load is below 260kg and 2.5 / 2.7 if above 260kg?

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Nuclear Nick
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Post by Nuclear Nick »

Am89 wrote: Wed Apr 29, 2020 1:04 am To confirm, is it 2.3 / 2.5 if vehicle load is below 260kg and 2.5 / 2.7 if above 260kg?
Yes. In your manual you will see this referred to as 'Part Load' and 'Full Load'. These load conditions are also set in the Tyre Pressure Monitoring System (TPM) which you will find in the Multi-Function Display (MFD).

The manual recommends checking the pressures manually at least every two weeks, noting that the settings apply at 20C ambient temperature.
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Tom 2000
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Post by Tom 2000 »

I believe the Fill Details adjust for temperature but I am not 100% on that.
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pmg
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Post by pmg »

Am89 wrote: Wed Apr 29, 2020 1:04 am To confirm, is it 2.3 / 2.5 if vehicle load is below 260kg and 2.5 / 2.7 if above 260kg?
What I do find surprising is the cliff edge of 260 kg suggested rather than a range starting at a low load raising to recommendation for max load.

I have been running my Macan at tyre pressures between the two shown on the basis that is probably right for my typical vehicle load. Overtime tyre wear will reveal whether this is bast or not.
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Nuclear Nick
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Post by Nuclear Nick »

Tom 2000 wrote: Wed Apr 29, 2020 12:43 pm I believe the Fill Details adjust for temperature but I am not 100% on that.
Yes Tom, that is correct. The display shows the delta between the desired pressure at that temperature and the actual so you know what to add or subtract without having to worry about ambient or tyre temperature.
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