5 Reasons your 4X4 is illegal

By Evan Spence 9 Min Read

It’s often said the best things in life are free. I think you can take that a little further and say the best things in life are also illegal.


Sure, we all like to do our top button up and pretend we’re high and mighty when it comes to mods on our rigs. Not like those other 4X4ers in their bogan chariots with complete disregard for the law. Don’t act like you don’t know who I mean! We’re sensible around here, just a couple of inches of lift, a slightly bigger size tyre and a few quality 4X4 accessories. The bare necessities while still staying within the confines of the law.

The only problem is, at some stage we’ve apparently turned into a nation of blundering idiots, not to be trusted with anything sharper than a blunt butter knife lest society fall into chaos. Sure, it’s never been officially recognised. But judging by the vehicle modification laws, the government clearly thinks it’s true. So while the powers that be are busy strapping us into our children’s stack hats it’s important to know where you might be running afoul of the constabulary.

Here are our top five things that people get wrong (from a legal standpoint) when modifying their 4X4s.

1. Fuel storage

If you’ve ever tried to get clarification on just about any law on the books you’d know it’s near-on impossible. That doesn’t mean you’ve been huffing petrol fumes already, just that laws are intentionally written vaguely. The positive outlook on this is it gives discretion to the police. The negative is you could easily mistake our law-makers for idiots. That said, we’re focusing on what you will get fined for, not what you could argue in the highest courts of Australia.


Carrying fuel inside your vehicle is a big ‘no-no’. Any potential fuel vapour leak can be catastrophic causing nausea, drowsiness, or even death. There are ways around this with venting but if you throw a jerry can on the back seat you will get pinged for it. Fuel must be stored in appropriate containers on the outside of a vehicle. Not the sides or the front, only the rear but not overhanging too far, and on the roof if there are no other options. Sheesh they don’t make this simple, do they?

2. Being over GVM

Truck weighbridges are a familiar sight if you’re doing any sort of regular driving, with huge fines for drivers and companies if a truck is overloaded. No-one really argues this as it’s just a ‘no brainer’. Too much weight for the brakes or steering to handle can cause the truck to carry too much speed and run wide through corners, or overpower the brakes and send a five-poster bull bar straight into the back of a family truckster off on a camping trip. Overloading a 4X4 is just as dangerous, and just as illegal.

Sure, you’re probably not going to put an extra tonne of cattle on the back of your 79 Series, but the effects of too much weight are the same nonetheless. It’s easy to do to, especially with today’s lightweight 4X4s. Know your vehicle’s weight limits and pack accordingly. The last thing you want is to void your insurance should the worst happen.

3. Too wide and too high

One of the easiest ways to get yourself a nice collection of defect stickers is increasing the width or height of your 4X4. Some of it makes sense, some of it makes us think our law-makers have no concept of physics. Big lifts are a ‘no brainer’. They make a 4X4 less stable, less responsive in emergency manoeuvres and create a whole heap of issues with lights blinding the poor sod in front of you. You can see why the laws are so strict with this, but a little more leeway would be nice.


The biggest ‘what the?’ law is width. Aside from the obvious issue of debris being flung out the wheel arches with massively offset wheels, there are numerous laws to comply with – from wheel width itself through to offset and even diameter. Without an engineer’s report or further certification it’s more or less impossible to fit a 10-inch wide rim or to deviate from the stock offset more than a size or two on any 4X4. As a general rule, if it looks tough rather than tasteful, it’s illegal.

4. Bullbar protrusions

If you’re getting run over by a steel bullbar travelling at 100km/h you’re in trouble. One doing 10km/h through a car park? You’ll probably be fine. Unless of course that nice smooth bullbar now has a whole bunch of knives strapped to it. The logic goes a pedestrian getting hit by a 4X4 with a bullbar shouldn’t be much worse off than one getting hit by a HQ Kingswood, not the monster truck from the latest Mad Max flick.

Things turn sour when there’s seemingly innocent accessories strapped to that smooth bullbar. Fishing rod holders can turn someone into a human sausage even at walking pace; even winch hooks, driving light mounts and those little whistle things that don’t actually keep animals away can all turn a ‘not serious’ incident into a news article. Nobody wants to be on the news for running over a nun while she does CPR on an injured koala, so keep the pointy bits off your 4X4.

5. Impending forward vision

SMIDSY. No I don’t have Tourette’s, it’s a well-known acronym popular with motorcycle riders. Sorry Mate, I Didn’t See You. Those six words are responsible for more motor vehicle collisions than whatever half-cocked scare campaign the media are currently running.

It’s easy to not see someone too. With modern safety standards, ‘A’ pillars are now thicker than ever before. The kids are screaming in the back seat because their wireless internet hotspot is causing grief with their iPads. Now to add to it there’s a dirty big Chinese lightbar strapped to the top hoop of your bullbar further limiting the important information getting through to you. Too bad that lightbar stopped you seeing the car in front’s brake lights, or that more kids walked in front of your 4X4 than came out the other side at the pedestrian crossing. Sorry Mate, I Didn’t See You. Keep things off the top hoop of your bullbar. If it impedes your forward vision, it’s almost certainly illegal.

If you’re modifying your vehicle, it will pay to look back on this article to make sure you’re staying within the lines of the law. The last thing you want is an unexpected fine because you unknowingly added something illegal to your rig. Save this link or ping it over to a mate who needs to read.

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