I wondered that too, because when I was in Colorado I noticed they have signs that say if the lights are flashing, you MUST have tire chains, but I saw in the owners manual that you should not put them on....
2006 HHR 1LT, 2.2L, Auto, Running Boards, Roof Rails, Sunroof, Chrome Package (54k miles) Built 5/24/06, Purchased 2/17/09
Mods: Molded Splash Guards, Chrome Exhaust Tip, Brake Light Cover, Stubby Antenna, Gutter Guard Grille, Chrome Tail Light Rings, TTR Sway Bar, 2LT Wheels
1999 Chevy Lumina (164k miles) Built 9/9/98, Purchased 8/14/06
1983 Chevy C-10 Scottsdale Pickup (166k miles) Built 4/83 in Flint, MI, Received 1/05