D10 is designed for a soft, wet, tacky track condition.
D20A is slightly tougher than the D10 and works well on crumbs or marbled tracks.
D30 is tougher than the D20A and performs well on cleaned off, dry-slick tracks.
RD40 is tougher than the D30 and is designed for harder, dry-slick tracks that begin to form a black groove.
The D20A will work well on cars that are easy on tires (i.e. Rookie, Jr. Honda) or on smooth indoor tracks that are not abrasive.
Because the D30 is slightly tougher than the D20A, it will be better on a wider spectrum of classes early in the indoor season.
Midway through the indoor season as the track gains grip and becomes more abrasive, it’s recommended to switch to a Hoosier A35 NY1.
The A35 is a high traction compound that will work well on tracks that lack grip, such as colder track conditions, slick or green track surfaces. The A35 will grip quickly with little heat and will be consistent throughout long green lap runs.
The A35 is more appropriate on indoor track surfaces that are tacky and high grip from the buildup of rubber in the corners.
The 31.0/4.5-5 will measure approximately 31” on a 5×5 wheel at 8 psi. Compounds available in this size include D10, D20A, RD40 & A35.
The 32.0/4.5-5 will measure approximately 32” on a 5×5 wheel at 8 psi. Compounds available in this size include D10, D20A, RD40 & A35.