I searched but didn’t find anything on this subject.
Is there some way to remove them from concrete?
My sidewalk is getting pretty black mainly from turning around while on the wheel.
Thanks.
give it time to remove marks from concreate. My teacher let me mount my 6’ unicycle in class, I almost got on but ended up falling off and leaving huge black mark on the wall. Any ideas for getting black marks off of painted walls?
For removing tire marks on painted walls: Try an eraser.
j.
For smooth surfaces a pan scourer might work, for concrete a stiff brush might do it.
Sarah
I left tyre marks on the walls of my living room while learning to ride. I just moved the sofa slightly so my housemates wouldn’t notice… 
Phil
You know, when I was a kid I remember leaving long skid marks with my Stingray. All it would take to remove them was getting down on my hands and knees and blowing on them…the powdered rubber just dispersed and the mark disappeared. I think that the marks from uni-ing are ground in there a little more deeply…I haven’t tried blowing on those. We use damp paper towels on the gym floor at our meetings, but that’s a whole different surface. I’d try one of those erasers that woodworkers use to freshen up a sanding disc…that ought to work.
unidaddy
I used to have contests with my friends to see who could leave the longest skidmark when braking on a bike. it was pretty fun…
but yeah, they’ll eventually go away by themselves, sort of like chalk drawings, they just disappear.
Heh, you should see inside my garage and my driveway. Tiremarks everywhere.
Thanks all
I know they will disappear in time, but I didn’t want the court “management” to get upset and say something. I tried sweeping with a very stiff-bristled broom, but that didn’t work too well.
Same here! I did them on my lil BMX b*ke when I was little. Good thing I’ve got a red tire on my uni or else there’d probably be more!
i think i would take a stiff nylon briste brush and some water and just scrub. Apply water liberally during scrubbing to help float the particles away.
.max
Me too. My garage looks just like tylers pic.
I’m assuming most of the marks were made while going forward right? So to erase them, it’s simple!: just ride backwards on the forward marks!
Pressure washer. They’re getting pretty cheap. The marks will return and look even blacker against a nice clean driveway though. Can’t win.
Great 
I will keep that one in mind. Maybe if I would have taken some video of learning, then I could just play the video backwards?
Trapper, good idea, I mean this funny: pressure wash the marks off the sidewalk and they blow right onto my neighbors trailer!
That would cause some interesting discussion, no? 
The marks are caused by friction between the tyre and the concrete, which abrades a small amount of rubber from the tyre with each sharp turn, and ingrains it in the porous surface of the concrete. This is made worse if there is considerable weight applied to the unicycle - for example by a rider who is built for comfort, rather than speed.
Kill two birds with one stone: smear the tread of the tyre with butter. This will reduce the friction, and therefore the abrasion. Also, you will have no butter to eat, and will have to make do with a low fat spread on your sandwiches, so you will eventually apply less weight to the unicycle.
An invoice for my consultancy fee is in the post. 