^^^^I remember several people having blow outs in the coal slag at Raton 2012. So when I bought my fold it cart, I got it with the foam filled tires. I even used it to haul out my quartered elk last fall. I forgot to clean it after that. I showed up at Phoenix this February with elk blood still inside.
I first used one years ago when we fished offshore. If the slip was 100yds or so from a vehicle we could pile in 250+ lbs of gear and transport it to and from the boat with ease and store the cart in a pull out drawer under a sofa in the salon. I've also used it to haul 200+lb yellowfin to a tournament weigh in when the scale dock was congested and we could miss the weigh in deadline. IIRC the only corrosion concern was the axle which responded well to a lanolin based anti-corrosion spray.