Karts are for adults but maybe not 9ft (2.7 meters) tall adults. The seats come in all sizes but I personally never cared for the fiberglass racing seats like you have. So maybe you are outgrowing the seat and approaching 9 feet tall? What will you do without a kart?!?
The āstainlessā looks chrome plated (as it explains with rust spots), but if it is stainless steel, it too can rust. Stainless is just rust resistant to a very high degree depending on the chromium and nickel(?) content in the steel. Just polish it and itāll be fine (steel wool, metal polish, Dremel, etc.)
I think you can sandblast the wheels with the tire on. A high powered sandblaster may destroy the tires if the blaster nozzle moves away from the wheel, but most of the time the sand bounces off. If I were you, I might hand sand those and paint. All I see is a little ācurb rashā as it is called. Be sure to mask off the tire extremely well when you paint the wheels or it will look like a hack job.
The a.i. robot says: Paint cracking is often caused by poor surface preparation, like painting over dirty, oily, or already cracked/peeling paint so the new layer doesnāt bond well. It can also happen from extreme temperature or humidity changes, applying the paint too thick, or using low-quality paint that dries brittle and canāt expand and contract.
And heās right.