Hurricane Carlos barreled westward off Mexico's Pacific coast on Tuesday, threatening several states with heavy rain, but it is expected to start weakening on Wednesday, the U.S. National Hurricane Center said. Carlos was 105 miles (169 km) south of the port of Manzanillo, blowing maximum sustained winds of about 75 miles per hour (121 kph) with higher gusts, and moving west-northwest at around 5 mph (8 kph), the Miami-based NHC said. Carlos is e…