It happens every year, people risky their lives and possessions by venturing out on area lakes and ponds.
Although there is no such thing as "safe" ice, here are some common thicknesses to remember.
4 Inches - Walking
5 Inches - ATV's/Snowmobiles
8-12 Inches - Cars
12-15 Inches - Trucks
If you're not familiar with a particular body of water, ask the local bait shop owner, or local who frequently use that water way.