There have been multiple tire threads, or threads that became tire threads. If you want, search "Vredestein". Somebody will bring them up every time there's a discussion, and it should take you to what you need. We've talked tires at least 4 or 5 times in the last couple of years.
If you feel your back end squirming, then raise the pressure, but be careful. Harder tires make oversteer easier to initiate. If you have a swing-axle car, you're already prone to snap-oversteer. I run 30 psi in my rear tires, but I'm on IRS and the car is really low.