What pressure for narrower winter tires?

[Laserbrain]

When changing from the 305/30R19 summer tires to 275/45R19 winter tires, what tire pressure should I use and why?

The sticker in the door jamb says to use 33 psi for the 305/30R19 OEM size tires.

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[Laserbrain]

This calculator says I should drop down to 27 PSI.

That doesn't make sense to me. I'd expect a narrower tire to need more pressure, not less.

https://tiresize.com/pressure-calculator/

 

[NightmareMoon]

Well, pretty much all the Mustangs have a Ford recommended PSI of 32 in the door jam, even the 18x8 wheels with narrow tires, to the PP1 with 255/275 tires and the 305 wide tire models too.

FWIW, that tire pressure calculator is solving for load rating, and since your new tire has a higher load rating, it has reduced the tire pressure needed, but IDK if that means it SHOULD be run at a lower pressure, just that it can be? IDK those things are weird and in my experience the wider tires with lower profile sidewalls can be run at lower pressures and grip/handle well.

Anyway, I'd go with Ford's 32 PSI as a good bet, and adjust from there based on tire wear patterns.

 

[Bikeman315]

When changing from the 305/30R19 summer tires to 275/45R19 winter tires, what tire pressure should I use and why?

The sticker in the door jamb says to use 33 psi for the 305/30R19 OEM size tires.

Tire size does not change air pressure. Your start point is whatever is in the doorjamb. You can always go up a pound or two. Only lower pressure if you’re going on the beach.

 

[Dana Pants]

I run 32f 28r cold for my snow tires. Mostly for even rear wear.

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