Just think about it for a moment. If the tyres are crap it doesn't matter how much horsepower and torque an engine is putting out or how sophisticated the disc brakes, ABS and suspension set-up are. The result will be poor grip, inability to transfer torque to the road, overlong stopping distances and rubbish handling.
They may be round, black and visually dull as dishwater, but make no mistake; tyres are one of the most fundamental components of any vehicle.