Largest tire size on 2011 with 20" stock wheels

[O-pie]

What is the biggest tire I can put on a 2011 Chevrolet with stock 20's without a lift or turning up the tortion bars?

 

[clrussell]

305/55 if you cut some. 285/55 will fit stock.

35-12.50 if you raise torsions and trim some