Near side front tyre more wear than off side front ?

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Took car in for it's MOT last week, now 7 years old. I've owned it since May 2006. It passed its MOT but the garage mentioned that 3 of my tyres had 4mm and one was just legal at 2mm. I have always fitted 4 tyres on the same day when required. Currently running Conti SP3s. Car runs and feels as good as ever on the road.
Any suggestions as to the cause of this and what I should have checked out ?
Car has now covered 70,000 miles.
Many thanks in advance for the excellent replies.
HT

[Spaceman_RS4]

Pot hole knocked the geometry out ?

[adsgreen]

If the track/tie rod bushes are wearing then could cause tiny movements that exaggerate wear that you may not notice (ESP damped through power steering).
worth double checking pressures and remeasure.

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Thanks for replies.
Adsgreen, I only drive the car and enjoy it very much. What pressures need checked and remeasured ?
HT