The interesting thing about legal questions is that sometimes they come as a complete surprise, as this one did and it forced me to look for laws that I didn’t know existed.  My correspondent wrote:

I write to ask the legality of reducing tyres on fire appliances to drive on sand for four wheel driving (4WD) in Queensland…

The QFES is about to introduce a new Fuso Canter with 2nd stage modification plates, of which the mods have nothing to do with the tyres or their pressures.

The vehicles have been badged with both road tyre pressures and sand driving pressures despite no mention on the compliance sticker for tyre pressures to be reduced to the level they profess.

The compliance sticker I refer to is the one in the door-well on the driver’s side of the vehicle.

The vehicles I talk about are Fuso Canters with cross ply tyres and the vehicle states the need to reduce from 415 KPa to 325 KPa when driving in sand.

I recall the need for heavy trucks to inspect the internal wall of tyres should they reduce below 80% of their specified pressures.  I don’t believe these vehicles would be regarded as heavy vehicles.

I believe that the Department of land water environment and parks (DELWP)  in Victoria got exemptions on their G Wagons to do so. I also believe it took DELWP a considerable time to get the exemptions from the tyre manufacturers but it came with very stringent caveats which made it virtually useless for them to do so.

This being the ability to reduce tyre pressures only to recover a vehicle and then only for the length of distance to become recovered. This being fairly useless when trying to get out of the way of a fire front.

They decided to go for nationally accredited training by way of safe driving practices to separate ‘weekend warrior’ 4WD thinking to that of a professional fire service using 4WD’s.

My questions are:

  1. Is it legal to reduce tyre pressures on vehicles for the purpose of emergency response in a 4WD situation?
  2. Is there are requirement to inspect the internal wall of tyres after they have been reduced in pressure?
  3. What is the actual law around reduction of tyre pressures when disregarding the specific pressures defined on the vehicle compliance plate?

I don’t understand many of those details but I don’t think the details of the types of vehicles etc are important.  I’m going to accept that the vehicles in question are not heavy vehicles within the meaning of the Heavy Vehicle National Law and Regulations.  The relevant laws therefore will be found in the Queensland road traffic legislation.

The Transport Operations (Road Use Management–Road Rules) Regulation 2009 (Qld) doesn’t mention tyres.   The Vehicle Standards set out in the Transport Operations (Road Use Management–Vehicle Standards and Safety) Regulation 2010 (Qld) Sch 1 do mention tyres – cll. 35-43 but most of those clauses don’t mention tyre pressure, and the one that does, cl 38 is not relevant to this discussion.  I can find no relevant regulation on tyre pressure.

The Commonwealth Department of Infrastructure, Transport, Cities and Regional Development says:

Before a new vehicle can be registered for the first time in Australia, it must meet the requirements of the Motor Vehicle Standards Act 1989 (the Act). The Act applies to all new vehicles—whether road motor vehicles or road trailers. Under the Act, new vehicles are required to be fitted with an identification plate (formerly known as a compliance plate). The identification plate provides a clear indication to the state or territory registering authority—and to the owner and the general public—that the vehicle is ready for use in transport on public roads in Australia.

The Administrator of Vehicle Standards’ Circular 0-3-2 Identification Plates And Approved Supply To The Market Vehicle Plates set out what has to be on an identification or compliance plate.  It does not include details of tyre pressure.

Vehicles must be fitted with a tyre placard (Vehicle Standard (Australian Design Rule 42/05 – General Safety Requirements) 2018, r 20). The placard must include:

… at least the manufacturer’s recommended:

(a)       tyre size;

(b)      tyre load rating;

(c)       speed rating; and

(d)      cold inflation pressure.

A reasonable presumption in law is that you can do whatever you like unless there is a law that says you cannot.  As far as I can tell the answers to the questions are:

  1. Is it legal to reduce tyre pressures on vehicles for the purpose of emergency response in a 4WD situation?

I can find no law to suggest that it is not legal.

  1. Is there are requirement to inspect the internal wall of tyres after they have been reduced in pressure?

Not that I can find (noting that I have not looked at the Heavy Vehicle laws).

  1. What is the actual law around reduction of tyre pressures when disregarding the specific pressures defined on the vehicle compliance plate?

I can find no obligation to have tyres inflated to the manufacturer’s recommendation. Where tyres are under-inflated and that creates a danger in that it impacts upon the vehicle’s handling then that may be evidence to support a conclusion that a driver was driving in a manner dangerous to the public or some such offence. For example, see the discussion in Suspended jail sentence for firefighter involved in a fatal accident (October 24, 2009)) which related to a driver’s conviction for the manner in which he drove a vehicle that ‘was top-heavy when filled with water’.  It was that impact upon the vehicle’s handling, coupled with the driver’s knowledge, that meant he was guilty of ‘dangerous driving causing the death’ even though he was driving within the road rules (ie on the correct side of the road, within the speed limit etc).  Equally driving a vehicle that cannot be properly managed because of low tyre pressure could be dangerous or negligent driving.

This post is not really about emergency law but about vehicle standards and I don’t claim any expertise in that area so I’d welcome any references to law that suggest a contrary conclusion.