Complex sentence: The official investigation also found evidence of a slow puncture in a rear tyre that, it was suggested, could well have caused a sudden collapse of the tyre with a consequent loss of control of the car.
Split into simpler sentences: The official investigation also found evidence of a slow puncture in a rear tyre. It was suggested, that this could well have caused a sudden collapse of the tyre with a consequent loss of control of the car.