Here is some sand car tires for sale, again note the narrow design and fin like rudder to penetrate the sand and steer, not big ballon tires to float like you might find on the rear.
Here are some quad sand tires
Here is a pure sand tire for a dirt bike
Here is what I think you need though. It is a 19" Harley Narrowglide front wheel with Aluminum hub and I believe an aluminum rim as well