Did change to all fours - to Michelin super sports - the front passenger tire keeps bursting, 2 tires burst in 3 months, what's the solution? These are supposed to be the best in the business, anyone found a solution yet ?

Those wheels are hot trash, pretty, but trash. I really don't like saying this, and I apologize in advance: Your problem will not go away until those wheels go away.

Did you read the post properly?
I have Michelin super sports (non run flats)
What other tires are you recommending?
I already switched out factory pireli run flats which were a total disaster

Yes, arguably the best in the business, but those are tires, not wheels. It is the wheels that are killing you, those are what have to go.

Another solution is to go slightly thicker with the Michelin. 255/40r21 front and 285/35r22 rear like the s63 AMG.

This car doesn't do well with the 21s. I went to 20s and haven't had issues in 40k miles on it so far.

My 2022 Audi RS7 has 22 inch rims and 285/30R22 tires front and rear and no issues in 4 years with bad roads. It's the design of the s class suspension etc that makes it prone to popping the tires along with their 21 inch rims. But the fact Mercedes went with thicker tires for the s63 tells me it's fine for the s580 as someone else did it on this forum without problem with rubbing etc.

Honestly the ride is much smoother and perfect with the 20s on the s class.

Yes W223 S63 tires size is the way to go. They will have a bit more of a side wall bulge since the S63 rims are wider.