The knobby tire is the most popular tire used on U.S.A made go-karts. These are ideal tires for off-road use. The best selling of these tires are the 145/70-6. Knobby tires are considered low pressure tires ( 6-10psi) the lower pressure makes for a smoother ride especially in non-suspension karts. Gopowersports offers a wide selection of quality tires at the best pricing.