What are part-worn tyres?
'Part-worn' tyres are those which have been used previously - in other words they are 'second-hand'. Most part-worn tyres are imported, mainly coming from continental Europe.

What are the potential problems with part-worn tyres?
Part-worn tyres are usually sold with about 50 per cent or less of their original tread remaining (legal minimum is 2mm) and may have a few thousand miles more motoring in them. However, despite their remaining tread, it must be appreciated part-worn tyres are nevertheless USED TYRES. As such their purchase and use should be treated with a degree of healthy scepticism. In many cases, such tyres will be perfectly sound. However, it is possible that they have been bumped up and down kerbs and over other obstacles. They may have been run over or under-inflated, and may have sustained irreparable and invisible damage to their structure.

The cost of part-worn tyres reflects their second-hand state and this no doubt contributes to their attraction to motorists. The purchase and use of part-worn, instead of new, tyres may enable some owners to afford to keep their vehicles on the road. The tyre industry continues to express concern about the sale and use of part worn tyres. However, it is important to consider the issue objectively and make a reasoned judgement about the real risks of using such tyres.

RoSPA's advice, like that of Trading Standards Officers, is 'let the buyer beware'. Whether the purchase of part-worn tyres is a good economic proposition or not, there can be little argument that a tyre which is only half worn but is in all other aspects sound, is likely to be safer than a tyre worn to the legal limit.

Before purchasing part-worn tyres always ask to see them inflated before they are fitted to the vehicle and check for any lumps or bulges. Part worn tyres should also be checked for signs of tyre aging as described elsewhere in this fact sheet. If they show signs of aging then you should not purchase them.

Source: http://www.rospa.com/