Chains or snow tires are being required on most highways in the mountains, including Highway 50 from Carson to Stateline and Kingsbury Grade from Foothill Road to the intersection with 50. Chains or snow tires are also required on Highway 395 south of Walker to Bridgeport.All three routes over the Sierra are requiring chains or four-wheel drive vehicles. There have been five accidents on Interstate 80 since 8:13 a.m., with most at Gold Run and one at Truckee.Snow that fell through the day on Saturday froze overnight and is making for some slick conditions.Heavenly Ski Resort reported 53 inches fell …