Tyre filler/bonding/glue for tyre gouge

[Alchemist]

Having fitted some brand new Hankooks to my E46 before I sell it have managed to get a gouge in the tread.

Driving to the local recycling centre (or dump in old money) and heard a clicking sound from the read wheel, pulled in to find a blunt Stanley blade embedded in the tyre. I've removed it and the tyre hasn't lost any pressure, so it's not caused a puncture but I wouldn't want to sell the car on if there's any risk this could cause a puncture/blow-out.

Is there such a thing as tyre filler that glues/strengthens the rubber if it's not punctured?

[sid10]

Safety first I would change the tyre as once cut the repair will never be as good as before, it is the only thing keeping you connected to the road and you wouldn't want to cause or be in an accident for a few pounds.