Caltrops can make urethane wheels go flat? That's no mean trick.
You really, really don't need anything that esoteric. Go get some relatively fine grain rocks--a pet store will probably have them for fish tanks--spread the rocks on the ground intermittently, find a seat and watch the fun.
Those look like teenage versions of the Plasma Cars that are all the rage amongst the under-fives these days.
I just saw a kid on the razor version last night at my daughter's skate party. I wanted to get my 4yr old one right away, but I don't think he's got the balance yet. Who am I kidding, I wanted to get myself one right away, but I can't yet justify it by getting it for my kid.
They're fun. I tried one out in a Walmart last year and went up and down the aisle till I fell off.
I was hoping the link would lead to a Segway.
Where you folks live, do you have commercials for these ridiculous things? I find them incredibly irritating -- they seem to think "the only shoe with a wheel in the heel" is a selling point.
And don't get me started on their irregular plural.
2: They let the air out of horses and camels, they should work on kids. Anyway, don't get hung up on the tire thing, see SCMT's 3:.
In the world I inhabit, nobody needs to advertise heelys because we see kids riding them all the time.