Manufacturer's recommended tyre pressure is just corporate CYA. They know nothing about you or your riding conditions. They are only concerned with product liability. You will never overload a tyre by pumping to max-pressure. That's all they care about.
For DOT rated tires, ALL tire OEMs must list the MAXIMUM cold pressure for the tire to perform at the MAXIMUM rated speed while carrying the MAXIMUM rated gross load without fail for
at least 1 hour. That's maximum-speed of tyre-rating, not bike's. So 2.9-bar on Z-rated tyre is for max-weight loading on tyre at 150mph for 1-hr. A W-rated tyre at 2.9-bar is for max-weight load at 168mph for 1-hr.
But performance, traction and safety is something completely different.
https://davemosstuning.com/tag/tire-pressure/
https://www.speedzilla.com/threads/w...n-36-42.28721/
https://www.fz09.org/threads/tire-pr...uestion.65072/
https://www.apriliaforum.com/forums/...tyre-pressures
https://www.riderforums.com/threads/...wisties.10224/