I mean, a media stunt can be done for charity rather than personal gain, but I'll trust your judge of their character.

But why only for 18 days? Artificial scarcity? Would there be any drawbacks to sell them without a deadline?

After those 18 days the music will probably be available through other means anyway..

18 minidiscs were leaked.

The total MP3 is 1.8gbs. The selling price is £18. It’s on sale for 18 days.

To me it seems clear that they just took the 18 number, decided to own it, and went from there on in everything else.

Prices and window were clearly set on purpose, starting from the number of minidiscs. The size of the originally-leaked material was actually different, so the final one might be coincidental or they might have “targeted” it with strategic padding to be cute.

You don’t have to be a cynic, this is Radiohead - they literally gave away what could have been their biggest-ever album, and don’t really need any publicity to sell out venues.

That’s the bit that makes it smell a little like a stunt. It’s too cute.

Quite. They could have released it for free, and chose to gave a big donation to extinction rebellion themselves. It's not like they're short of cash.

https://en.mediamass.net/people/thom-yorke/highest-paid.html

But they don’t make any money on the sales. They are donating all the income to charity.

Why fake a charity? That’s not how Radiohead does things.

When’s the last time Radiohead was in the news like this?

No band makeshifts substantial money from album sales anymore anyway. It’s about concert sales.

Guess who has a tour starting in three weeks?

Every time Radiohead release a new album it makes the news. They don't need to pull fake stunts to get noticed

Not Radiohead. A band who sell out the tours anyway.

Yorke skipped the band’s rock and roll hall of fame induction. That was the most recent thing.

Their tours sell out instantly, they don’t need marketing scams to promote them

Thom's tour sold out in seconds, they don't need any extra publicity.

The only real coincidence here is the MP3 size equaling the number of discs, but I think it’s possible to target a total size with MP3 encoders so that could even be set on purpose.

Additionally, only the .zip of VBR encoded MP3s from Bandcamp totals up to 1.8 gb [0]. The original leak was 1.38 gb.

[0] Screenshot of available formats on Bandcamp: https://i.imgur.com/5Ra1VmS.png

Plus they're granting us the right to download this music, and Ulysses S Grant is the 18th President. It all fits!

Because it's a charity drive. It creates a sense of urgency and people are more likely to donate

This material is only really interesting to hardcore fans, who will jump at the chance very quickly. I bet most sales will happen in the first week, if not the first two days, so there is little to gain from keeping it up longer. By setting an end-date, they also add a bit of urgency for the less-hardcore fans who might be sitting on the fence, using FOMO anxiety.