Is it 5 or 6 lug. Most tractors and implements used a 6 lug rim. Is your 430 a loader tractor? IIRC, the 430 is considered a "construction" or "CK" series. You could probably run both 15" and 16" wheel but the 16" would raise that side of the bucket just a bit. Not sure if it would make a lot of difference. Just depends on what you are doing with it.