In winter, you must be prepared for snowy or icy mountain roads and cold temperatures. Tire chains can be required on any park road at any time from fall through late spring.
Chain control is in effect here when roads are snowy and slippery, usually November through March. State law requires that ALL vehicles (including 4-wheel/all-wheel drive) carry tire chains or cables when entering chain-control areas.
When chain control is in effect, all vehicles must carry chains (and may have to install them) in order to drive to sequoia groves and designated snowplay areas. If you do not have chains, plan on renting or buying them before entering the parks. Road conditions and chain requirements can change rapidly; for example, you may not need chains when you enter the park but they may be required by the time you leave.