As a complicating factor military units are often referred to as light, mediumor heavy. In that context light means a unit that is readily portable by virtually any means and particularly by airlift. Heavy means a unit equipped for maximum combat power with few if any concessions toward weight or portability. Medium describes every unit in between. For example most of the vehicles such as GS trucks issued to a light unit would weigh less than 10 tonnes whereas a heavy unit would have many weighing several times that much.

Currently an upper limit for ready portability of a vehicle by fixed-wing aircraft is generally held to be 18 to 20 tonnes. That limit seems to have become accepted because it approximates the load of the widely used C-130 Hercules freighter at normal maximum take-off weight.

Of course 20 tonnes may seem too heavy to be referred to as light. However, a scan across the current variety of armoured vehicles suggests there could be natural boundaries predicated on weight, and that two such boundaries occur at about 20 and 40 tonnes all-up weight. Perhaps that is simply the result of subjective bias rather than Darwinian-style analysis. And even if the latter applies there could be other natural boundaries. But regardless of observation or analysis it is anyway convenient to postulate 20 tonne intervals between three main classes of armoured vehicle described by weight as light, medium and [/B]heavy[/B].

Those boundaries were in fact suggested – originally or otherwise – by MAJ John C. Larminie in ‘The operational requirements of light armoured vehicles,’ International Defense Review , 11/1987, p 1487-1492. Having never met Larminie this is a good time to comment on the pleasure of reading his articles.

If his suggested boundaries are accepted then light can be used to describe any armoured or unarmoured vehicle which has a maximum combat laden weight of less than 20 tonnes. Light could be similarly used to describe a military unit in which every item of equipment weighs less than 20 tonnes. The term heavy could be used to mean a vehicle weighing more than 40 tonnes, and also a unit which has many such vehicles and other similarly heavy items of equipment. In the middle a medium vehicle would weigh at least 20 tonnes but less than 40 tonnes, and a medium unit would have mostly medium and also light vehicles, but might additionally have a relatively small number of heavy vehicles as in Table 2.

Boundaries at 20 and 40 tonnes are much easier to remember than a contrived Queensbury-style classification. And exceptions for light vehicles and light units under say 10 tonnes could be described in specifics. For example a parachute unit could be described as X-tonne meaning than each of its vehicles and items of equipment weighed at most X tonnes.

The 20 and 40-tonne boundaries have been described and adopted here for convenience. It is not additionally implied that tracks become superior to wheels at either boundary. As a general observation wheeled vehicles are well suited to on-road/on-track movement and are particularly useful for operational mobility. However, for off-road movement, obstacle crossing and tactical mobility it is apparent that track laying vehicles – despite the hazard of breakage – become superior to wheeled vehicles at some weight well below 40 tonnes and probably below 20 tonnes.

Such superiority can be argued against. But it is well supported from historical times by the assessments of various analysts and commentators such as:
CAPT Edwin W. Besch, “Armoured reconnaissance Vehicles”, Interconnair –II-81, p B1-B8;
Paul Hornback, “The Wheels Versus Track Dilemma”, Armor, March-April 1998,
re-printed Defender, Winter 1998, p 19-20;
Maj. J. C. Larminie, “Soft-ground performance of military vehicles”,
International Defense Review, 4/1988, p 383-386;
Don Loughlin, “Wheels vs. Tracks: Rebuttal”, Aviation Today, 2000,
[www.c4inews.com/reports/wheelsvtracks.htm (cache)] d-l 21July2006.

Anyway back towards the thread. The purpose in this post was to develop the concept that there are three basic classes of armoured vehicles: light up to say 19.9 tonnes, medium from 20 to say 39.9 tonnes and heavy from 40 tonnes and upward. At the lower end below 10 tonnes, the X-tonne convention or classification can be used for specific vehicles and units.

The ‘Larminie’ weight-based classification may be thought contentious or unnecessary. However, a following post will use it as a framework against which to consider the types and armament of infantry carrying armoured vehicles. As an extension to ‘perceptions of mechanised infantry’ that post is likely to be contentious.