Interestingly, the TGV record was broken by an unmodified Velaro-D train recently. Standard rolling stock, used the week before for normal transport, used a week after for normal transport.
The TGV record is about half the speed of sound, which means the wheel rims are bordering on supersonic, so it's not a simple thing to talk about exceeding it.
The middle a the wheel moves at the same speed as the vehicle relative to the ground. (X + 0)
The top of the wheel moves at twice the speed of the vechile relative to the ground. (X + X)
Put another way, the top of the wheel must go faster than the vehicle or it does not rotate.
It's an odd diagram to draw out, as that result is pretty counter-intuitive.
[0] http://www.mobility.siemens.com/mobility/global/en/interurba...