For PR4 GTs, tire life will improve quite a bit if you go up two to four psi at both ends. I ran my recent set at stock pressures initially until about 4000 miles, when I noticed the wear being more than I expected.
The old-timer service manager here says run at least 40psi up front on FJRs and most other full-size bikes. So far, my experience supports that.
I also have PR4s (not GTs) on my ZRX1100 and the typical Kawasaki heavy steering effort at low speeds is greatly reduced by going +4psi at both ends. Since the tires were on the bike when I got it and I have no information about their mileage, I can't say about wear rates being affected.
2018 Versys 650LT in the hands of the Missus
2007 Ninja 250
(Recently departed) GPZ/ZX1100E, best bike I ever had.
And some others over the course of the decades.
In the avatar: 1966 Velocette Venom Thruxton and 1967 BSA Royal Star.