Lazy axles are a popular combination for a 750kg trailer.
Axles without brakes are manufactured in a variety of sizes from 39mm Round for a small box and jet ski trailers up to 3t for farm trailers.
750kg is the limit for unbraked axles. Larger axles up to 3t are available to be used on-farm applications. An example is a 6t tandem axle with no brakes.
39mm round axles are at their maximum rating and cannot be upgraded.
Furthermore, the addition of Landcruiser wheels de-rates 39mm round axles by 20%. Therefore the new rating of a 39mm round axle would be 600kg.
When considering an upgrade from 750kg for a box trailer, brakes will be required on at least one axle.