I have a red fox lxt as the logo says but it is very similar to the manco dingo kart. I do not know what year it is as it does not indicate it.
I am having trouble finding a new 8 inch rear wheel. ( live action axle) My old one ripped the welds out and is non funcoinal. I cannot find a new one that is the correct size anywhere. The parts sites say its a 8 inch wheel but when i measured across the top rim it said 9 inches but idk how diameter works on wheels.
Rims are not measured at the outer lip, but rather the bead area. The bead is the surface between the lip of the rim and the ridge just inside of the lip. This is where the tire makes contact with the rim. From your picture the lip stands off about 1/2 inch from the bead, so the rim size is 8 inches in diameter. The width of the rim is measured from the inside of the lip to inside of the lip. Again, from your photo it looks like the wheel lip sticks out about 1/4 inch on both side, so the width of the rim is 7 inches.
How is the wheel attached to the axle? It looks like there is a single nut that holds it on. Is there a keyway in the axle and wheel to prevent the wheel from spinning on the axle? If so, you may have a harder time matching up the two. Make sure you get all of your dimensions (axle diameter, length/width/heighth of the keyway/key and the depth of the barrel on the wheel the axle passes through) and contact the wheel manufacturer for their recommendation. If the key is slightly oversized, you may be able to grind it down to fit.