Capricorn rim reamer
Italian company Capricorn have released this rim reamer tool for 1/8th and 1/10th scale wheels. The tool is simple to use, fitting into the back side of a rim and using the axle hole as a central rotation point, it allows your to change the thickness of the wheel by shaving the material away. A rim with thinner material is softer and so provides more traction.
Source: Capricorn [capricornrc.com]