Toyo recommends setting tire pressures per OEM recommendations:
http://www.toyo.com/tires/tire_basics/inflation.html
So... 46 to 50 is pretty high, even for hot. When I've run street tires on the track, I set them for about 32 front, 30 rear and can heat them up about 10 psi to about 40 psi front, 38 psi rear or thereabouts (Vette numbers using Kumho Ecsta MX street tires which are slightly softer than the Toyo T1Rs).
Your balance may be off due to the high pressure but I doubt it. What is also possible is that due to the water used to get the tire on the rim, the tire can rotate on the rim after being mounted, which obviously will mess up the balance. I mark my track tires with chalk at the valve stem the first time I take them out and check the chalk vs valve stem position when I come back in. If it has moved, I have it rebalanced. :cheers