Because going up 1" diameter is stupid when a smaller diameter will the do the job better in every way?
I like the M5 19's, not a fan of the M6 19's. Though they're only 0.5" wider than the 220M's though, so might as well go with the ZCP's which have a better offset for our cars. Interesting that the M6 gets 0.5" more wheel width than the M5. The M6 rear offset at ET19 is going to be a tight fit with a wider tire, need more like ~ET27-30 for the wider tires to fit in 19"