Bridgestone Kart Tires are a very popular tire for sprint track racing across the world. Bridgestone makes all kinds of tires, and is made by the same company as Firestone Tires.
Why exactly are bridgestone tires and firestone tires made by the same company? Well, Bridgestone was started in the US in the early 1900s and Firestone was created on the other side of the world in the 1930s. Long story short, Bridgestone bought Firestone and now they are the same company, and have been for a while.
An old Bridgestone Kart Tyre on 6 inch wheel
Bridgestone makes primarily tires for 5 inch wheels, but this is a picture of a six inch wheel.
The tires made for superkarts by them are for six inch wheels.
The rest of Bridgestone's tires are all for five inch wheels, and vary in grip from a 38 on the durometer (tool to measure softness, lower the number, the softer it is) to 68.
They make kart tires for the CIK (Commission Internationale de Karting) homologation. The CIK does this to reduce driver expenses, and what it basically means is they require certain tires to be ran in their races.
Another series they make tires for is the Vortex Rok series.
They offer slick tires and rain tires for the Rotax Max series, a popular series all over the world, that is just getting bigger and bigger.
Bridgestone Tires are popular among just hobbyists, racing in amateur tracks across the world and Bridgestone makes tires for them as well.
They make indoor kart racing tires, because indoor surfaces are usually slightly different, and they also make tires for rental race karts, that are very popular for people who just want to show up and race.
You have seen the series Bridgestone makes tires for. They are impressive and wide. It's not hard to see why they have such an impact and will for many years.