If you zoom it enough you can read the text albeit only barely. The second circle goes as far as Assago and Sesto San Giovanni; the third goes as far Rozzano an

If you zoom it enough you can read the text albeit only barely. The second circle goes as far as Assago and Sesto San Giovanni; the third goes as far Rozzano and Rho; the fourth goes as far as Cornaredo and Pioltello. Based on this the first circle should be the circonvallazione esterna (viale Liguria etc.).