Owen Danter was last seen in the Doncaster area on December 15 and was reported missing three days after.
More than two weeks later, police have widened their search for him and believe he could have travelled to the Highlands, particularly around the Cairngorms.
The 43-year-old is from the Brough area but has links to North Yorkshire and is known to visit rural areas.
Officers are appealing for the public’s help to find Mr Danter, focusing on Aviemore and Grantown-on-Spey.
He is thought to be driving a grey Range Rover which has roof bars front and back, side skirt steps, and is fitted with a static tow bar.
Mr Danter is described as being 5ft 10ins with short brown hair and a beard.
When he was last seen, he was wearing a black jacket, a blue polo shirt and black boots. He is also believed to be wearing a black cap.
Anyone with information regarding Mr Danter’s whereabouts should contact Humberside police on 101 quoting reference number 230 of December 18.
