[JABCAT]

Originally Posted by MineralGreyMetallic

Max pressure on the tires I listed is 50/51.

I think I’m probably good at 43 cold.

You don't drive on tires near their max pressures. The correct cold pressures are probably 32-34.

[MineralGreyMetallic]

From the manual ...

For speeds over 100mph without M Driver's Package

I have 285/30 R20 in the front, so looks like I need to come down to 38 from ~42.

In the rear I have 305/25 R21, so 43 looks like it might be ballpark.

[JABCAT]

Originally Posted by MineralGreyMetallic

From the manual ...

For speeds over 100mph without M Driver's Package

I have 285/30 R20 in the front, so looks like I need to come down to 38 from ~42.

In the rear I have 305/25 R21, so 43 looks like it might be ballpark.

Unless you're driving at continuous speeds over 100 mph (i.e., racing) every day, those pressures are not applicable. Per the manual you should be 32/~36