Attempts by the Scottish Environment Protection Agency (Sepa) to reduce the risk by removing the tyres have so far failed, prompting calls for a tough crackdown.
Tyre dumps are a recognised fire hazard, with at least 10 major blazes reported across the UK within the last two years (see table below). Combustion of the rubber can produce clouds of thick, black smoke, making it dangerous for aircraft.
Sepa has assessed an unlicensed waste tyre store on Lyon Road in Linwood in Renfrewshire "as a potential fire risk ahead of the coming Commonwealth Games". The site is "of concern to the Scottish Government," said a report to Sepa's board meeting last week by the chief executive, James Curran. "This site is politically as well as environmentally sensitive as it is on the flight path of Glasgow Airport," he added.
Sepa has served an enforcement notice on the site's operator to remove the tyres, but the deadline had to be extended to May 31.
It is also demanding that the operator apply for a waste-management licence. "By the end of March only 17,000 tyres had been removed as compared to the 47,000 stated in the company's rescue plan," Curran said.
Mary Church, head of campaigns at Friends of the Earth Scotland, said the site would be a "potential legal nightmare" if it ended up in court, adding: "Illegal tyre dumping is becoming a major problem and this site typifies both the kind of major hazard that can build up and the failure of waste companies to deal with that hazard.
"Sepa has given the company a second chance to put things right but severe action will be needed if they do not deliver this time. With less than 11 weeks to go to the Commonwealth Games, sorting this site is doubly urgent."
Sepa pointed out that the management of the Linwood site changed late last year. "There is no waste-management authorisation issued by Sepa in place for operation of waste-management activities on this site," Sepa's head of operations, Kenny Boag, told the Sunday Herald.
"Sepa has now required the operator to apply for a waste-management licence, in addition to continuing to take necessary enforcement action to mitigate risk."
According to Boag, there were currently estimated to be around 100,000 tyres on the site. "The operator has submitted an action plan to remove tyres from the site by the end of May 2014," he said.
"If the operator fails to remove the tyres by this time Sepa will consider further enforcement action in line with our enforcement policy. We are continuing to actively pursue the removal of the tyres and are in regular contact with both the operator, and other relevant parties, to explore all avenues for resolving this issue."
A Scottish Government spokeswoman said: "The Scottish Government is supporting Sepa's efforts to protect the environment, the interests of the local community and to mitigate any risk to events like the Commonwealth Games.
"We are working with Sepa to give them the enforcement tools they need to tackle cases such as this in a robust, proportionate and timely manner to better protect Scotland's environment and communities."
The site's operator, Clann Waste Management, did not respond to a request to comment.