Joe's question prompted me to search around for an answer. I thought that they would want to use as light a spare as possible since it would never be used. I found these pics which I believe answers the question.
This next pic isn't a real car but it is a highly detailed model.
All three depict the type of tire as represented by Carrera. It appears the Fly car may be the one that is wrong. That is unless there were some cars with full size spares which I didn't find.
Mike