The rear wheels of a tractor are larger than the front ones. The case with a combine is reverse. All the wheels of a truck are of the same size. The rear wheels of small Korean trucks are much smaller than the front wheels. At the first glance, it is irrational – two stepneys are needed. However, such an approach offers an obvious advantage in operation.
The thing is that such small trucks are usually loaded by hand. Small wheels provide low positioning of the body – only about 80 cm. The lower the surface, the easier is the loading. For a big truck, this property is of no importance, so trucks with the carriage capacity over 3 tons have wheels of the same size. It is unlikely that the idea to load such a truck by hand will strike any Korean!
An interesting compromise solution allows coordinating the truck construction with the operation conditions.