At TKO as the dirt is really dry and loose.... Use large pins tires like the jconcept double D, goose bumps. Do not use barcode or mini pins as they will wear out quickly in TKO and donot provide enough traction.....
hard packed clay means really hard clay surface, it is almost like onroad. But the top is still clay and dark brown in color. These kind of track is really flat. (depend on how packed the track is use mid or small pin tires)
Blue grooved is hard packed clay after lot and lot of run and the track surface is covered by rubber from the tires. So the color turn in the a very dark blue/ black color. For dirt track blue grooved have most traction (other than carpet or astroturf). Have not seen any track like this in HK yet...... (use barcode or mini pin tires)