Summertime tire pressures - what counts as "cold" for setting tire pressure

[Dark Sprite]

So where I live daytime temps in the summer months range from 35-50ºC (95-120ºF), but during the work day my car is parked in a temperature controlled car park. What this means is that setting a "cold tire pressure" at manufacturer specs at 32psi when the car is sat outside means that when I leave the work car park at the end of the day my tires have cooled to a level below the outside ambient temperature and are down to 30 psi, whereas if I set the "cold tire pressure" at 32 psi when parked inside then once I've been on the highway for a while they can get up to 38 psi. Maybe I'm overthinking it, as the owners manual does state a max hot tire pressure of 38 psi (non-HP DH) but that's for track not road use.

It doesn't take long to get up from 30 to 32 psi once I've left the temperature controlled parking, so would I be better off setting my cold tire pressure to 32 psi when the car is outside (obvs not in direct sunlight or better still after being left overnight) or inside? Basically I have two options for what constitutes "cold" .

To be clear, I've not had any issues with grip, so I suppose this is more relevant from an even-tire-wear perspective...

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[Zig]

Cold is unused for 8 hours

 

[Dark Sprite]

Cold is unused for 8 hours

I don’t think you read my post before replying.

 

[GhastlyTT]

Undriven and at ambient is the intention. In the morning or in the car park should be relatively similar, no? Manufacturer cold pressure is really just to combat underinflation, which typically causes more overall wear and damage to a tire than overinflation. 95 in the morning to 120 in the afternoon is about a 3 psi swing in cold static pressure, which shouldn't contribute much to irregular wear. I'd set 31psi cold personally and monitor wear.

 

[lcseds]

I check the pressures mid morning on cloudy days. On sunny days, the temps are too different because of direct sun. But you are correct, don't over think it. a pound here and there is nothing.

 

[NegativeMultiplier]

I've been running my car in track mode more often (after learning traction control is in fact not fully disabled in track mode) and it has the tire pressures as the default screen in the cluster.

I deflated my tires to be about 32-35 PSI when they're warm for more contact with the road, and I've noticed when I take it out of the garage in the morning the pressures are between 26 and 28 depending on the ambient temperature. I'd say anything between 5-10 PSI lower than whatever the reading is when you've been driving around for an hour, depending on how you drive, is your "cold" pressure read.

Just bear in mind this may lead to the car thinking its pressures are too low if you're not careful and go too low.

 

[Junkyard Dog]

I set mine at more like 29, drive at 32-33.

If you are driving around at 38 psi, you are driving on the inside (middle) of the slightly swollen tread, and you will wear out the middle of the tire tread sooner. Plus, you are giving up a very slight amount of traction compared to lower pressure. This is not enough of a reduction to have "issues with grip," but the traction will be higher with 32 or 33 psi as compared to 38 psi.

So better traction and more even wear across the tread await you if you get that pressure down some.

 

[BrownsReds]

I don’t think you read my post before replying.

The definition of "cold" in this case, is not the ambient air temp but the length of time after last driven which is 8 hours, i believe

 

[ZXMustang]

I wait until the next morning then set them to 30. Then just let them do what they want day to day. Only when they start showing less than 30 the next morning after sitting all night, will I redo them back to 30.

 

[Zig]

I don’t think you read my post before replying.

Basically I have two options for what constitutes "cold" .

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