as far as im aware there is no need to advise your insurance company that you have "uprated" the tyres from standard spec so the likely hood of them not paying out is slim unless as previously stated it was a very high speed crash then they would look at how the car was set up, maybe they would pay out for the claim but issue you with a CU30 offence for driving with defective tyres or a CU20 for causing danger by unsafe vehicle