Audi A3 ABS Light

[SMIHTKID1]

Hi

I have an Audi A3 Quattro and the ABS light keeps coming on (not on all the time). I took it back to the garage I brought it from (non Audi dealership) and they say its due to the tyres being of different tread ? does this sound True ??

[MORELLO]

I would say that's complete bo@#ocks, and if not , would love to hear their explanation!