they appear to be iron, however the van runs like a raped ape, 0-60 in under 9 seconds, (around 8 last time I clocked it) empty. Also it tows like no tomorrow, it's pretty bad when a full size van towing about 8000 pounds up a mountain is pulling away from the mini-van behind it. (we had stopped to secure the straps on the trailer and we couldn't catch dad in my van.)