During certain times of year (September through May) many states have “chain laws” in effect. This means that when you pass through these states while the chain laws are in effect, you must have chains on your tires.
You can be sure these laws are in effect when snow is covering the road especially on roads with ascending grades. But so as not to guess, drivers are notified via 511 traveler information, electronic message signs and other media outlets.
States That Have Chain Laws
Each of these states have different laws so follow the link to their respective DOT website for specific information