There are 2 main sized karts available for dirt racing. Dirt karts are available in junior & senior size. Karts required for midget & rookie classes are modified junior or bitumen chassis. The wheelbase length of the kart gives its junior or senior nickname.
Most dirt brand karts use 28mm frame tube & 40mm aluminium axle with different length wheelbase and/or width.
Click on the kart logo for which karts that brand offers for your class.