Thirty-three-inch tyres transform a 4WD’s look and off-road ability, but they’re not free at the bowser. The fuel penalty is real, though it’s often smaller in dollars than people fear. Here’s what actually drives the extra consumption, with figures hedged as a 2026 guide — your real result depends on your vehicle, load and driving.

How much extra fuel do 33-inch tyres use?

There’s no single number, but as a guide most owners see a fuel-economy hit in the range of roughly 5–15% after jumping to 33s with an all-terrain tread. One worked example from Auto Expert put a reader’s claimed 10% increase from a set of aggressive all-terrains at about $8 a week — meaningful over a year, but hardly ruinous. The point: the percentage sounds scary, the weekly dollar figure often isn’t.

Why do bigger tyres cost more fuel?

Three things stack up:

All-terrains are, as Auto Expert bluntly notes, “the least economical tyres you could possibly buy before going to hardcore mud tyres.” Mud-terrains cost even more. If economy is your priority, the tyre-type you choose matters as much as the size.

Does the extra weight really matter?

Yes — rotating and unsprung mass is worse for economy and performance than the same weight carried in the body. That’s the same reason heavier wheels and tyres affect braking and acceleration; we cover it in do heavier wheels wear tyres faster. Choosing a lighter-construction tyre where your use allows, rather than the heaviest LT available, is one lever. The honest trade-off between toughness and weight is in our LT-construction guide.

Should you re-gear the diffs after going to 33s?

A taller tyre is like fitting a taller final-drive ratio: it drops engine revs at a given speed, which can help highway economy in theory but hurts acceleration, towing and low-speed control, and makes a manual’s clutch work harder. For a big jump — particularly to 35s — a diff re-gear (numerically higher ratio) restores the original drivability and can actually improve real-world economy under load, at a cost of typically a few thousand dollars installed. For a modest 33-inch step on a torquey turbo-diesel, many owners skip it. Weigh it against how you drive; a re-gear is money, so treat the decision as general information and get a quote from a driveline specialist.

How to limit the fuel penalty

You can claw some of it back:

• Run the correct tyre pressures — under-inflation is a bigger economy killer than most mods, and worth checking every couple of weeks.
• Choose an all-terrain with a lower-rolling-resistance compound rather than the most aggressive tread you can find.
• Keep rolling diameter sensible and your speedo recalibrated so you’re not unknowingly speeding (and burning more fuel).
• Strip unnecessary weight and drive smoothly — look ahead, accelerate gently.
• For big builds, consider the right tyre for a two-inch lift before over-sizing.

The 4WD community guide from 4WDing Australia ranks big aggressive tyres among the top ways to wreck economy — worth reading before you commit.

Frequently asked questions

How many extra litres per 100km? As a guide, roughly 0.5–2.0 L/100km for a mid-size 4WD going to 33s, depending heavily on tread and load. Measure your own before and after.

Do 33s ever improve economy? Rarely at the pump, but taller gearing can lower highway revs. Any gain is usually cancelled by extra weight and rolling resistance.

Is a re-gear worth it just for fuel? Usually not on a 33-inch step; it’s more about restoring towing and drivability. On 35s it’s a stronger case.

Will bigger tyres affect my warranty? See do bigger tyres void your warranty — not automatically, but keep records.

Bottom line: Expect 33-inch tyres to add roughly 5–15% to your fuel use — often only a few dollars a tank, but real over a year. Tread choice, weight and gearing drive it. Correct pressures and a sensible tyre choice limit the damage; a diff re-gear is about drivability as much as economy. Measure your own figures before and after.

All figures are a guide for 2026 and vary widely by vehicle, load, tread and driving style. Confirm re-gearing and fitment with a driveline or tyre specialist.