Officers from Wolverhampton Council’s Trading Standards team joined forces with Driver and Vehicle Standards Agency (DVSA) Market Surveillance Unit to carry out the test purchases.
A total of 11 part worn tyres were bought from a number of traders.
Two were found to be selling tyres with nails embedded in them and clearly visible and should have been spotted during pre-sale checks.
Other issues included the age of the tyres on sale, with some being up to 12 years old, and the fact some tyres were not marked with the warning ‘Part Worn’ which is a legal requirement.
Trading Standards officers will now be considering what action to take against each of the businesses.
The mystery shopper exercise built on work started last year when city businesses selling part-worn tyres were visited by Trading Standards and DVSA and advised of their legal obligations.
Councillor Steve Evans, cabinet member for city environment and climate change at Wolverhampton Council, said: “We are all watching our money at the moment and tyres can be expensive, so it is understandable that people may consider buying part-worn to keep cost down.
“It is legal to buy part-worn tyres, but motorists need to be confident that the tyres on offer are safe.
"Old or damaged part-worn tyres are a serious danger to all road users and are not worth the savings if they end up costing you your health or damaging your vehicle.
“The mystery shopper exercise has brought some important issues to light and we will return to these businesses and continue to work with them to ensure they are aware of the legislation to prevent the sale of unsafe tyres.”
Further advice on buying part-worn tyres can be found from the DVSA by going to movingon.blog.gov.uk/2022/12/07/buying-part-worn-tyres-what-operators-need-to-know/