Let's face it, we're all interested in saving a few pounds where we can. However, one economy we would argue you should never make is purchasing part worn tyres.
In the UK, it is perfectly legal to to sell part worn tyres. Their sale is governed by the Motor Vehicle Tyres (Safety) Regulations Act 1994 - part of the Consumer Protection Act. Any part worn tyre must pass a series of tests and be clearly and permanently marked as Part Worn. Under current legislation, it is down to the vendor to ensure that the safety checks are carried out and tyres marked as Part Worn.
In a recent study into the sale of part worn tyres by Tyre Safe, found that 97% of Part Worn tyres were being sold illegally and were not marked as pet worn. To add to this worrying fact, they also found that a third (34%) of their sample had faults or damage which meant that they shouldn't have been offered for sale.
Furthermore according to TyreSafe, on average, a part worn tyre can cost more per mm than a brand new tyre. The tread will wear more quickly on an already used tyre than on a brand new tyre. Part worn tyres can be sold with tread as low as 2 mm - the legal limit for tyre tread in the UK is 1.6 mm therefore at 2 mm the tyre is already 94% worn. Stopping distances in the wet at 50mph can increase by 12m between a new tyre at 8mm of tread and a worn tyre with a tread of 1.6mm. The dangers are clear.
There is no way of knowing the history of a part worn tyre - so we would always advise buying new tyres and not taking the risk.