The visit came after a public rally and fireworks in Pyongyang to celebrate the launch of the Hwasong-15 ICBM, in violation of international sanctions.
At the Amnokgang Tyre Factory, Mr Kim complimented workers for manufacturing the tyres for the 9-axle missile truck without relying on imported equipment.
He called for efforts to raise production to "satisfy the daily-increasing needs in developing the country's economy and beefing up national defence capabilities," the North's official Korean Central News Agency said.
Mr Kim had tasked the factory to make the tyres for the "great event in November", the agency reported.
The Hwasong-15 is believed to have reached the highest altitude ever recorded by a North Korean missile.
It flew 600 miles (950 km) before splashing down in waters near Japan and is potentially capable of striking targets as far as 8,100 (13,000 km), which would put Washington within reach.