Hi, so today I was doing a bit of research as to our legal standing in regards to selling part worn tyres and retreads, and where we stand when a 
customer gets a puncture fixed but the tyres are worn to or past the legal limit and what I found was very interesting!
Firstly it was on the Road Safety Authority website where I found a full write up on part-worn and retreads that all my questions were answered:Â RSA_Part-Worn_Consultation_Document
But just to summarize:
1. There are no specific regulations for part-worn tyres in Ireland and, as such, they can be legally fitted and used on vehicles providing they meet with the Construction and Use of Vehicles Regulations 2003.
2. It is the legal responsibility of the owner and driver of a vehicle or combination of vehicles to ensure that, when it is used in a public place, it is in such a condition that it is not liable to endanger other road users.
3. Buying part-worn tyres may offer substantial savings to consumers at the time of purchase. However, when consideration is given to the shorter lifespan and the cost per millimetre (mm) of usable tread on a part worn tyre, new tyres may actually prove to be better value for money for the consumer in the long term. Consider the example of a part worn tyre which costs â¬30 and has 3.6mm of tread remaining. This tyre will have 2mm of available tread wear before the minimum legal depth of 1.6mm is reached. Therefore the cost of the tyre can be equated to â¬15 per mm of available tread. On the other hand a new tyre costing â¬80 will have 8mm of tread or 6.4mm of available tread wear, which equates to â¬12.50 per mm or a 17% cost reduction.
In addition to the increased costs in the example above, the vehicle owner will have to fit three sets of part worn tyres to get the same life as one new set of tyres.
4. These condition checks should be done on all part worn or retread tyres:
·        Any cut over 25mm which is deep enough to reach the ply or cord
·        Any internal or external lump, bulge or tear
·        Any ply or cord exposed internally or externally
·        Penetration damage that has not been repaired
I guess the moral of the story is that you should either go for new tyres
 or make sure your dealer checks them fully!