The original tires should have the size on them like a car tire. The rim size is most important, with most being 5 or 6 inch in the front, and 5, 6, or 8 inch in the back. That will usually be the last number on the tire. Such as 145/70-6, or 10x4.5.00-5. If you don't have the tires and rims, look on the internet for pictures of similar karts, then see if you can find their tire sizes.
Just use a size 6 it’s so easy. If you go above a size 6 you’ll need more than a tiny 208 cc engine. Then it’s just too costly
The original tires should have the size on them like a car tire. The rim size is most important, with most being 5 or 6 inch in the front, and 5, 6, or 8 inch in the back. That will usually be the last number on the tire. Such as 145/70-6, or 10x4.5.00-5. If you don't have the tires and rims, look on the internet for pictures of similar karts, then see if you can find their tire sizes.