Interpreting labels in Load Center

[Alectrician]

What would be the point in tinning them?

To keep the strands together?

Use your sidecutters and twist them together. You could have been done with this project by now

[Norcal01]

That's different. You can use #8THHN up to 50A.
I would not derate the neutral for such a circuit. You can proabaly find #8 solid at a supply house.

You can't use # 8 SOL anymore in conduit, see 310.3 2005 NEC