I got a piece of plexiglass about a square foot and drilled a hole in the center. Bought a cheap tiny tripod and took just the top part off and bolted it to the plexiglass. Then put just the hook side of velcro on the plexiglass. It grabs the carpet perfectly and the whole thing removes easily.
The numbers are a paper number sign taped on with painters tape.
The doughnuts were fun and no biggie since we got 7 runs that day.
Just a reminder that you want your tires to have lower pressure. The harder your tires are, the less flex they will have, and the more they will tend to want to slide. But not so low that they roll. Which is easily seen by scuffing on the sidewalls. It won't scuff the sidewalls very much, but if you have some then go up on the pressure. If you start high on your pressure and you don't see any scuffs then you can try dropping a pound or so on each run and check your tires again.
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