never suffered from this on my ST FR184, and I’m picky about noise, but I have heard of people putting additional layer of soundproofing under the boot false floor to absorb it on theirs. Conti’s aren’t always quiet, but it’s an expensive experiment to replace tyres on a whim. But the original Contis on my previous E-class estate were much noisier than the Michelin HP Primacy I replaced them with.
This seems a bit of a bodge, but it might work. Got any old carpet you could use as insulation?