Glad that 4-in line idea didn’t head down here, the only side by side arrangements we have are rows of 8 etc on floats.
Was there a sound reason to go for such an arrangement?
Most axle load restrictions can be traced to some road engineering feature.
The most common design criterion here was bridge beam spacing at a nominal 8’-0", hence the 8’1" wide spread which (hopefully) only ever had one axle per bridge beam.
A close bogey had 14t for the group and as the axle spacing increased, the allowable axle load also increased.
We went to 9’1" (16t) and later versions went way further until the whole concept was binned and tri-axle (22t+) became the standard.