Robert Finlayson, 22, from Hamilton, was found dead at around 4.35am on Monday on the B7078 Carlisle Road, just north of Draffan Road, Blackwood in South Lanarkshire.
Police believe Mr Finlayson, known as Robbie, was struck by a light-coloured Mercedes Actros tractor towing a tri-axel rigid step framed trailer. The driver of the vehicle may not have been aware that they had struck Mr Finlayson, the police added.
Mr Finlayson’s mother, Angela, said the family would be unable to move on until the investigation had come to a conclusion.
“I really just can’t put it into words how much we’ll miss him, every aspect of his life. How can you put into words how important one person is?
“Some days it’s just like he’ll be through the door for his dinner, other days we realise that he won’t be.
“We can’t move on because we can’t do anything, we can’t put Robbie to rest therefore we are just sitting waiting as well.
“I think for his brothers and for all the rest of the family its important that we have this conclusion, that we all know what happened so that we can piece together Robbie’s last movements and understand what happened to him.”
My Finlayson is believed to have been hitchiking when the incident occurred.