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Discussion Starter · #1 ·
I am wondering whether it's necessary to adjust tyre pressures for altitude when driving in the mountains? In our case, we're in the Swiss/Italian Alps at the moment.

Having done a web search, if I'm at 32 PSI at sea level at 20C then the equivalent pressure at our current 1500m location should be 26.79 PSI - around 5 PSI less.

Next week, we'll be going over the St. Bernard Pass to the Aosta Valley, reaching an altitude of 2,469m over the Pass, where the equivalent pressure would be 24 PSI - around 8 PSI less.

Now, it's obviously infeasible to keep adjusting the tyre pressures constantly, as we move between the valley, our holiday locations and cross the higher passes of the Alps. But I did wonder whether we should make some adjustment down to cater for the altitude effect.
 

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I've driven the Alps several times and never adjusted my pressures and all was fine TBH, I didn't even think about it.
 

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Dunno about altitude, but the TPMS on my GR Yaris would always alert when the temperature dropped significantly in winter. It did show the actual pressures of each wheel so you could ignore the possibility of a puncture.
 

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Discussion Starter · #6 ·
Thanks for all the advice. After further reading, I think I may have misunderstood the physics. Inasmuch as it's the outside pressure that drops, so this will increase the measured pressure of the tire. e.g. if it's, say, baseline 32 PSI at sea level then it'll be 32+'x' PSI higher at 1500m, so I'll have to drop it by 'x' to get back to the baseline - I never reduce the baseline pressure itself. And from what everyone says, the 'x' is going to be so relatively trivial that it's not worth the adjustment anyway, especially in comparison to parallel changes in load (it was loaded-up to get here, but is now unloaded), and temperature (which has ranged from 15°C [59°F] to 33°C [92°F]).
 

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IMay I politely suugest that you are overthinking this
I have been up high in plenty of places and never bothered or even thought about the tyres
 

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Discussion Starter · #8 ·
No problem. I definitely am. I measured the pressures in the underground garage here at 1500m and it was only +2 PSI over what it was at sea level. Perhaps driving over the St. Bernard Pass tomorrow, it'll get to +3.5 PSI, which isn't going to be anything dramatic.
 
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