Banpei's two door panda Trueno from Japan

[Koen]

I think you're calculation is wrong by a few mm ..

The ET is measured from the center. So your rim is 1/2" wider to each side (7.5 - 6.5" /2) which is about 13mm. Then you move the center 19mm further inwards (25-6mm) so the total extra "poke" would be 32mm which is what you measured If you fit the same tires the tire-stretch would also help you with clearance.

You even need a spacer in the rear if you want them to sit in similar position to the arch as it's 22mm in the rear and you have 41mm of room. But my experience is that the solid rear axle doesn't make it easy to run flush fitments as the axle moves left to right and doesn't camber in under suspension compression. This is probably why people like the incredibly solid springs for the AE86. Then the suspension won't move and you can run great fitment

And I believe your car is lowered a bit so the length of the panhard also has impact. If this is stock, this usually means that left and right are now different so you need an adjustable panhard rod.

I would just start with trying to fit them and see what happens