Meguiars wheel brightner, online shops like cleanyourcar, elitecarcare etc
Can mix it 4:1 for heavy stuff and 10:1 for general clean up.
Is about 4 litres, so mixed 10:1 is best value you can get.
Maybe use neat on insides if it's that bad, or wet and dry 1000 2000 and 3000 grit.
The smoother the finish, the better your wheel sealant will form a barrier, and will be harder to get wheels in such a state again.