Dad and I (well, mostly Dad) built the original in '66 or so. It was a replica of the car he and mom honeymooned in back in '56. I found a pic of mom in the car, looked like they were waiting for a ferry on that trip.
Anyway, the spares got tossed and my next '56 was a Strip Fowl (!) version from the local SS Kresge, and I seem to recall the kit having those front runners. At one time I had 'em in the tire box, but that was a long time ago.
Sure would be cool if they came back in a retro release. I'd tip over like a drunk if R2 decided to just re-release all the trophies in their 'white box' configuration, which was some of the most beautiful box art in modeling history.