C-Ports are made of 100% recycled rubber from tires. And all modern tires are made from vulcanized rubber (note: this does not mean it comes from the planet Vulcan, Spock’s home). Therefore, no C-Ports will not melt because vulcanized rubber does not melt.
Back in the 1800s, rubber products were prone to melting in the hot weather. Why did this happen? The rubber back then did not undergo the same process as it does today to chemically change the properties that makes it heat-resistant.