F12 tyre pressure for upgraded Scuderia wheels

I have been putting custom wheels/tires on my cars for decades. Start with stock pressures. Observe tire wear as the miles go by. You want even wear across the tread--center versus outer edges. That means that the pressures are good for your driving style.

 

That's exactly what I would do.

You can also shortcut this process by paying close attention to how much the sidewall is rolling over in cornering. You are looking for "just right" - if it rolls over too much, you're underinflated. If it doesn't roll over enough, you're overinflated.

A lot of autocross and track guys put a small paint mark on the sidewall, but you can also just observe the natural wear marks on the outermost tread blocks.

This is a good visual indication of what you are looking for:

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• 1st off get a good alignment so you can be sure all 4 tires are in spec to how the meet the pavement.

• Do the "chalk test." Enthusiasts often use this method to ensure even tire wear.
  1. Mark the tread face of the tire with a line of chalk.
  2. Drive the vehicle a short distance in a straight line.
  3. Examine the chalk line. If the chalk is worn away only in the center, the tire is overinflated. If it's worn away only on the edges, it's underinflated. Even wear across the tread indicates proper inflation.

When you "plus-size" from a 20-inch wheel to a 22-inch wheel, you typically use a tire with a much shorter sidewall to maintain the same overall wheel diameter. This change significantly reduces the tire's air volume, which means a higher PSI is needed to carry the vehicle's weight.

This is all done if you want to get technical with it all. But remember the car came with 20" from and rear tires and they will roll over a little more in the corners and provide best grip. Going up to 21/22" you now have a very skinny fragile sidewall that is stiff and does not want to roll over in a corner. This will lift up the inside of the tire and into towards the center. So the issue will become how much tire do I want to keep in contact with the road vs. running less psi to keep more tire on the road with less air pressure but then run risk of damaging tire sidewall and/or denting or bending the wheel edge barrel.

Never rely solely on the maximum PSI printed on the tire sidewall. This is the maximum safe pressure for the tire, not the recommended operating pressure for your vehicle.