Upgrading to bigger 4x4 tyres is one of the most popular modifications among Australian drivers.
But the big question is:
Are larger 4x4 tyres actually legal in Australia?
The answer is:
👉 Yes — but only within strict limits.
At Autosport Tyre World, we regularly help customers upgrade their tyres safely and legally. Here’s what you need to know before going bigger.
Why Do Drivers Fit Bigger 4x4 Tyres?
Larger tyres can provide:
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Increased ground clearance
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Improved off-road capability
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Better traction on sand and gravel
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A more aggressive appearance
However, bigger isn’t always better — especially if it compromises road legality or insurance.
What Makes a Tyre “Illegal” in Australia?
Tyre legality depends on:
1️⃣ Overall diameter
2️⃣ Load rating
3️⃣ Speed rating
4️⃣ Vehicle state regulations
Each Australian state may have slightly different modification rules, but the key principle is:
Tyres must remain within the allowable overall diameter increase and meet manufacturer safety specifications.
How Much Bigger Can You Go?
In most cases across Australia:
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Passenger vehicles can increase overall tyre diameter by up to 15mm
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Many 4x4 vehicles are allowed up to 50mm increase in overall diameter
⚠ Important:
These limits vary depending on:
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Vehicle type
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GVM upgrades
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Engineering certification
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State regulations
Always check your specific state authority guidelines before modifying.
What Happens If Tyres Are Too Big?
Oversized tyres can:
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Alter speedometer accuracy
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Affect braking distance
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Stress suspension components
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Increase fuel consumption
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Make your vehicle unroadworthy
Most importantly:
🚨 Insurance companies may deny claims if your vehicle is found to be illegally modified after an accident.
Do Bigger Tyres Require Engineering Approval?
Sometimes, yes.
If your tyre upgrade exceeds the legal diameter increase, you may require:
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Engineering certification
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Mod plate approval
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Updated registration details
Failing to do so can result in:
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Fines
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Defect notices
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Insurance issues
Load & Speed Ratings Still Matter
Even if the size increase is legal, your tyres must:
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Meet or exceed manufacturer load rating
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Meet speed rating requirements
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Be suitable for your vehicle weight and intended use
This is especially important for 4x4 vehicles used for towing or heavy loads.
Is It Worth Going Bigger?
Ask yourself:
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Do you regularly drive off-road?
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Do you need extra clearance?
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Or is the upgrade mostly cosmetic?
For many drivers, a quality All-Terrain tyre in factory size provides excellent performance without legal complications.
Final Advice Before Upgrading
Before fitting larger 4x4 tyres:
✔ Confirm your state’s legal diameter limits
✔ Check load and speed rating compliance
✔ Consider how it affects handling and braking
✔ Get professional advice
Choosing the right tyre upgrade can improve performance — but doing it incorrectly can create serious risks.
Looking for Legal 4x4 Tyre Options?
Browse our:
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4x4 Tyres Australia collection for compliant upgrade options
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SUV Tyres Australia range for balanced on-road performance
Or contact Autosport Tyre World for guidance tailored to your vehicle and state regulations.
👉 Upgrade smart. Drive legal. Stay protected.