If you engage in the practice, you should do so knowing the possible ramifications.
I gave an example to
@grampi of a couple I knew of, who were running a car tire on their Goldwing. Of course he called it a lie...
Desperation to save a buck will make some people do bizarre things.
Due to incompatible bead profiles and a sidewall which is not designed for the same loading as a motorcycle tire, the car tire lost the bead while trying to negotiate a curve, and they crashed. They survived the crash, with some serious, but luckily not life-threatening injuries. But the insurance adjuster denied the claim when the car tire was noticed, due to improper equipment, which had been a direct cause in the crash.
So it begs the question: Why have insurance if it will be void anyway?