Hi to all !
I'm currently using this method for all the 1/20 scale tyres from F1 kits:
- a real drill
- this ...
- a piece of sandpaper 150
- and a... portable vacuum cleaner, lots of dirt !
put a double-side piece of scotch under the sandpaper and stick it to the table
"plug" the tyre into the tool
set the drill at MINIMUM speed.
And after CLEANING after each pass the sandpaper with the vacuum cleaner, and spending approx 5min for each tyre, you'll have this result:
hope someone will find it useful !