I see Kaltire doesn't care any 235/40/20 size tires.
On the other hand, tire rack carries 235/40/20 Michellin pilot sport A/S and the highest rated out of 4 tested tires. I'm likely going to get these to replace the 20" run flats that BMW put on so they wouldn't have to supply a spare and sell winter tires to boot. Shame on BMW...
https://m.tirerack.com/tires/test-re...34YR0PSAS3PLXL