Sounds like road noise and the duration of the hum changed as you slowed. Are you on concrete roads or asphalt. And I suspect new tires are not going to help much and may make it worse if you go 200TW or lower.
It's been said already but 90% of the wrecked Supras are front end -- get it together kids -- meaning you can get a used hatch w/glass for cheep cheep cheep. There are probably 10 to choose from at any given time. I looked into this option for my RB A91 so I would not need to repaint but only...
Absolutely - And you can point people to it when they ask questions so everyone can get the same info. Good luck with the next adventure and keep doing what your doing in the unlock space.
On the stock PSS I ran 26 cold and hit 38 hot at HPR, sunny 90 degree day. I presume your getting way to hot starting at 30 and your 3rd+ lap(s) are probably suffering alot.
It's a corrosion inhibiter and it leaks out when it's hot... park it outside for a few 90 degree days, wipe away, and you shouldn't need to deal with it again.