What has the spare wheel got to do with this thread?
From my very limited knowledge of
HID lamps, I believe they require a large current to start, then run on lower power once on. Similar to flourescent tubes.
If there was any chance of damage from short bursts, the
HID lights would not be connected to the 'flashing' circuit, so I would not worry.
On a personal note, I would not make a habbit of flashing, it is far more dangerous and misleading than people think.