Here's an interesting thing.... Valkyries and Goldwings are big, heavy motorcycles. The majority of their riders are into cruising versus corner carving. Bike tires are not really up to the task of carrying such large weights over the distances these riders expect, so the stock tires are a compromise, thick, hard carcasses that don't last the distance. At over 300.00 per tire change, people are always looking for alternatives.

Car tires on the rear. The right sizes are available, they stick and last, being afforded Much R+D through a much higher sales volume. Prices are significantly cheaper too, for the same volume reason. Sparks much debate. I for one will never ride one, but my riding is significantly different than your average big bike rider, I love curves and routinely wear out the sides of my tires long before the center tread. I want stick and linear grip throughout my lean angle, not less grip the more I lean. I digress. For many, it works well. To each his own. Anyway, this monologue is the introduction to this YouTube clip, where you see a bike wearing a car tire on the rear leaning and scraping in a parking lot....(1:57)