The wheel sizes you mentioned seem a little off, but then I have no idea as to what size wheels are used on a 206. 5″ wheels are the most common. Only occasionally have I seen 6″ on endure karts. Look at the tire size on the tire. Example: a 7.10 x 5 would indicate a 5″ rim.
For the time being, if there is a shop or a kind fellow racer at the track, ask if they will mount up your tires. And watch closely. Mounting tires is not that hard if it’s warm out. But it does take some technique.
LAD Specialties customer / tony kart / rotax / kt100