The best way to get good traction on hard packed snow is to:

Putting chains on your tires is an effective method to enhance traction when driving on hard packed snow. Chains are designed to provide additional grip on slippery surfaces, creating a firmer connection between the tires and the road. When the vehicle encounters hard packed snow, which can be slippery and challenging for standard tires, the chains help prevent slipping and improve control, allowing for safer navigation in winter conditions.

Using snow tires is also a recommended practice for driving in wintry conditions, as they are specifically designed with tread patterns that improve traction in snow and ice. However, the chains can offer an even more immediate solution in particularly severe conditions. Maintaining lower tire air pressure can enhance traction as well, but it can also lead to reduced handling and increased tire wear. Carrying heavy weights in the trunk may help improve the grip by increasing the downward force on the tires, but it is not as efficient or reliable as using chains or snow tires.

Overall, while there are several methods to improve winter driving safety, putting chains on your tires stands out as a direct and effective approach to maximizing traction on hard packed snow.