Does Changing Wheel Size Void Your Car Insurance in Australia?

Upsizing to bigger wheels is one of the most common car modifications in Australia, and one of the most misunderstood when it comes to insurance. The fear that a set of aftermarket rims silently cancels your policy is largely a myth — but there’s a real risk hiding underneath it, and it comes down to disclosure, not the wheels themselves.

Does bigger wheels void insurance automatically?

No. Fitting larger or aftermarket wheels does not, by itself, cancel your policy. What creates the risk is failing to tell your insurer, or fitting wheels and tyres that aren’t road-legal. Australian insurers treat almost anything altered from factory — including aftermarket wheels and wider tyres — as a modification that should be declared. Canstar notes that anything added or altered after the car leaves the factory is typically a modification and should be reported, and that undeclared changes “could potentially affect the approval chances of any claims you make.”

The real risk: your duty when you take out cover

Since 5 October 2021, consumer car insurance in Australia is governed by a duty to take reasonable care not to make a misrepresentation to the insurer, which replaced the old “duty of disclosure” for personal policies under the Insurance Contracts Act 1984. In plain terms, you must answer the insurer’s questions honestly and carefully when you buy or renew. If they ask about modifications and you don’t mention your wheels, that can be a breach.

According to legal analysis of the reform, if you breach that duty the insurer can:

• Reduce a claim proportionately — pay only what they would have, had you disclosed the modification (which may mean a higher premium or excess would have applied); or
• Avoid the policy entirely if the misrepresentation was fraudulent.

Importantly, an honest mistake isn’t automatically a breach — the insurer has to show you failed to take reasonable care. But “I didn’t think wheels counted” is a weak position when the application asked about modifications.

When are modified wheels most likely to bite?

Two things multiply the risk: whether the modification was declared, and whether it was legal. Wheels that push you outside the legal size limits, breach the placard load rating, or would attract a defect notice are the ones most likely to sink a claim.

How to change wheels without risking your cover

1. Keep the fitment legal. Stay within the VSB 14 diameter and track limits (see the safe wider-tyre range), meet the placard load and speed rating, and get a modification certificate if the change needs one.
2. Tell your insurer before or as soon as you fit them. Declare at purchase, at renewal, and mid-term if you modify during the policy.
3. Confirm they’re covered. Ask whether the aftermarket wheels are insured for their replacement value — some policies cap or exclude non-factory accessories unless listed.
4. Keep paperwork. Receipts, a fitter’s invoice and any engineering certificate help both compliance and a smooth claim. National Cover notes documentation proving compliance also tends to price better.

Will bigger wheels cost more to insure?

Often, a little. Larger or performance wheels can lift premiums because they cost more to replace and can be a theft target. That’s not a penalty for being honest — it’s the correct price for the risk, and it’s far cheaper than a refused claim. If cost is the concern, weigh it against the full cost of fitting bigger wheels and tyres in the first place.

Frequently asked questions

Do I have to tell my insurer if I change my wheels?

Yes. Aftermarket or larger wheels are a modification, and you should declare them when you take out or renew cover, and if you modify mid-term. See our full guide on disclosing aftermarket wheels.

Can an insurer refuse a claim over undeclared wheels?

They can reduce a claim proportionately, and in cases of fraud avoid the policy entirely. The risk is greatest when the fitment was illegal or contributed to the incident. Honest, declared, legal wheels rarely cause a problem.

Does staying with the factory wheel size avoid all this?

Genuine factory-size replacements generally aren’t treated as a modification. It’s changes away from standard — bigger diameter, wider, aftermarket rims — that trigger the disclosure question.

Will legal, declared wheels still raise my premium?

Possibly. More expensive wheels can lift the premium because they cost more to replace, but that adjusted premium is what keeps your cover valid — much cheaper than a declined claim.

This is general information, not financial or legal advice, and insurance terms vary between policies and insurers. Read your Product Disclosure Statement and confirm your specific situation with your insurer.