The diamond-cut alloys are completely flat with the tyre so the slightest time you go near a kerb the alloy makes contact with the kerb whereas with a more "normal" alloy the tyre protrudes out from the alloy as you can see in the picture above. I'm not sure about the punctures either, but...

I have a Qashqai Tekna with 19" diamond-cut alloy wheels on it and I'm so fed up with them. You only have to look at a kerb and it knocks chunks out of them and I've had three punctures on the nearside front now in 1.5 years and two different tyre places have told me this is a common issue with...