Yes passenger car tyres rated at 530kg each so thats 2120kg on a 550kg trailer with a 540kg car going on it - I have no problems with that. The spare isn't there yet because I only got the trailer a few days ago, drove it home and parked it in the garage and been busy since.
I got the trailer fitted with Ford hubs so that my Toyota Hiace light truck wheel/tyres will fit. They go for about $150/set on Ebay every now and then.
Edit: After walking through the pits of EC with Neil on Saturday and looking at the condition of most of the trailers (boat tyres/wheels, wooden slats, home built, 20yo rusted, etc) I have no hesitations about my trailer at all