The first, of course, would be the issue of hubcaps falling off. Magnetic hubcaps could cling magnetically to the lugbolts or even the rim itself to help prevent it from being jostled loose while in transit.
The second would be to help prevent that famous "Oh fudge!" scene from 'A Christmas Story' from reenacting itself at your expense.
Magnetizing the outer layer as well might help collect FOD off the streets as you drive... but I don't expect everyone to be on board with that.-- 21 Quest, Dec 07 2013 Picking up FOD at low RPMs on the onramp to fling them off once you get to full speed... I guess you could incorporate a gutter to catch the objects mechanically when they get flung to the edge, but then your wheel won't be balanced.-- scad mientist, Dec 09 2013 With some kind of rail gun, you could pass bits of iron past the bottom of the hubcabs to induce forward movement and the top to perform braking. Or possibly the other way around. Expect some interesting video of the ensuing disaster either way.-- not_morrison_rm, Dec 09 2013 random, halfbakery