you can actually buy a " Kart tyre Lathe"  to enable tyres to be shaved and profiled to achieve various benefits.  1) tru'ing the diameter to give a better size match and ballance  2) removing the bulk of rubber on the tyre face to give faster temp build up and reduce weight  3) produce a specific diameter tyre to suit a particular  " stagger" set up for certain race tracks  4) " profile" the tyre surface to improve the grip and cornering characteristics.      ( imagine a tyre with different radii on the edges, or a tyre with one edge larger than the other ?? )
   These techniques are commonly used in the USA for oval and dirt track karting.   ...tricky with the trusty surform.
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