That sounds exactly like whats wrong, i had new rears fitted a few weeks back and the fronts have about 3mm left. Also the cars been lowered, not sure if that would have an effect? Cant see why it would though..
To the guy who asked they are the normal road f1's.
Looks like new front tires then, thanks
once you have had the front tyres replaced - you will need to monitor the tyre pressures as part of the problem you are having could be that the pressures are out - this would mean that the rolling radius of the tyres would be different to that of which the ECU is expecting to see from the ABS sensor. this is exactly how tyre pressure warning light systems work. (not on the z it doenst have a TPC system)
obviously a very slight drop in tyre pressure wouldnt give this fault - but if the front tyres are on 3mm and havent had the pressures checked for a long time they are bound to be out which would mean the rolling radius isnt matching the figure the ECU is expecting.
Its a very simply concept - sometimes these are the things we forget which end up causing bigger problems.