Biggest tyres for a MU-X RJ: will 33s fit?

On an RJ MU-X, assess 265/70R17 before committing to 285/70R17. Compared with the cited 265/60R18 reference, the 33-inch-class 285 adds 55.6 mm in nominal diameter. Choosing a 17-inch rim does not by itself make the complete tyre smaller.

Australian 2021-on RJ MU-X with factory examples from Isuzu's 25.5MY specification. The wheel example is the standard RJ selector. X-Terrain, earlier RF and converted vehicles need separate applications.

What is the biggest tyre to consider?

The 25.5MY grades use 17x7, 18x7.5 and 20x7.5 factory wheels with different tyre packages. Pick the exact LS-M, LS-U, LS-T or X-Terrain reference and check the spare location before treating a larger tyre as a touring upgrade.

The table is a decision shortlist. It does not claim a tested maximum tyre size for every stock vehicle in this generation. The source-backed sizes, dimensions and conditions below let you narrow the package before an installer checks it.

What tyre sizes came on this vehicle?

These are scoped examples, not a size chart for every year or variant. Match the tyre placard and wheel markings on your own vehicle. Read the original reference.

Read the tyre sidewall

How much bigger are these tyres?

The largest example here adds 55.6 mm in nominal diameter, or 27.8 mm in nominal radius, relative to 265/60R18. These are arithmetic dimensions from the sidewall code, not measured sizes of a particular product. Tread, construction and the manufacturer's specification can change the real unloaded diameter. The radius change is not a promise of ground clearance on a loaded vehicle.

What real tyre specifications change

The following are exact product rows from the tyre makers, checked on 13 November 2026. They illustrate dimensions and rim approvals, not a recommendation that each product suits every vehicle in this guide. Load and speed suitability still need confirmation.

Read the exact version in the quote. An LT, passenger or XL version may have a different construction and specification despite sharing the same nominal size. A supplier must match the chosen tyre to the rim, load and vehicle, rather than using the inch label alone.

The metric calculation is wheel diameter in inches × 25.4, plus twice the section width × aspect ratio. Flotation dimensions such as 35x12.50R17 are nominal too.

Will the biggest option fit stock or with a two-inch lift?

A wheel that turns freely on a level workshop floor has not completed a clearance check. Ask the installer to assess the exact tyre and wheel at both steering locks and throughout suspension movement, including loaded compression. Include body liners, mudflaps, suspension components and the spare location.

A suspension lift changes the resting position. It does not, by itself, prove that a larger tyre clears the body at full compression. Lowering the wheel offset can gain room on one side while moving the tyre closer to another obstruction.

The 25.5MY specification gives distinct 17, 18 and 20-inch packages. Do not carry a tyre approval across those packages merely because the vehicle is an MU-X. X-Terrain's separate application also needs to be respected.

Which size would we choose for daily driving or touring?

Mostly road and everyday use: start with a suitable tyre in the manufacturer-designated size. A different tread can change the look without increasing diameter.

Touring and mixed tracks: compare the original diameter with 265/70R17. In nominal terms that changes diameter by +27.6 mm and section width by +0 mm. Decide whether that change is useful before arranging a fitment check.

A larger off-road build: price the complete 285/70R17 package, including the wheel, clearance work and speedometer check. Establish whether a lawful approval path exists before buying the package. Comparison dimensions are not an approved upgrade list.

Are 33s or bigger tyres legal in Queensland and Victoria?

The inch label cannot answer that. The 285/70R17 comparison is 55.6 mm taller in nominal diameter than this guide's 265/60R18 reference. That reference is a comparison input, not a finding that it is your vehicle's largest eligible manufacturer option.

Queensland: for eligible MC, NA and NB1 vehicles, the current guidance allows up to 50 mm more tyre diameter, subject to the other requirements. For an eligible off-road 4WD, up to 75 mm combined lift can avoid certification when it comprises no more than 50 mm suspension lift and 25 mm tyre-radius increase, with no body blocks. A certified LS9/LS10 lift still has a 50 mm tyre-diameter cap. Queensland's prescribed design-new or UN diameter method must be used; this article's nominal calculator is not a legal pass/fail result. See the Queensland rules and worked example.

Victoria, including Melbourne: VSI 8 provides a conditional 75 mm combined-lift alternative for eligible off-road 4WDs, with up to 50 mm suspension lift and 50 mm more tyre diameter. A suspension kit must be designed and tested for the make, model and variant at the combined height, with a written suitability statement retained. Coverage, full-travel clearance and ESC requirements also apply. See Victoria's full conditions and VASS pathway.

A two-inch lift is 50.8 mm, so a product's marketing name is not evidence that it stays within a 50 mm limit. Confirm the actual lift and complete package. Vehicles outside these categories, above 4.5 tonnes GVM or registered elsewhere need the applicable rules.

What to confirm before buying

• Your exact grade, build date and original designated tyre size.
• The chosen tyre model's published diameter, load and speed specification and approved rim width.
• Loaded clearance through steering and suspension movement, including the matching spare.
• The applicable state tyre-diameter, track and combined-lift requirements, with any approval documents obtained before the work.

Questions owners ask before fitting bigger tyres

Will a two-inch lift stop all tyre rubbing?

No. It changes the resting position, while the tyre must still clear at the suspension's compression limit and both steering locks. Check the exact tyre dimensions, wheel width and offset. Do not alter steering stops merely to create tyre clearance.

Can I put 285/70R17 on the factory MU-X 17x7?

Do not assume it is approved. Check the exact tyre maker’s rim-width range. For example, the published LT285/70R17 versions in the product table start at 7.5-inch rims, which excludes a 7-inch rim for those versions.

Does an all-terrain tyre in the same size need a fitment check?

Yes. The manufacturer tables above show why nominal size is not an exact physical measurement. Check the particular construction, published diameter, approved rim range and load/speed requirements before replacing the original tyre.

See the size and stance on your own Isuzu MU-X RJ

Once you have a technically suitable shortlist, compare the look against your own paint, tray, canopy or touring equipment. See wheels and tyres on your vehicle in Nordak. A generated build is a visual concept and cannot confirm mechanical clearance.

Read the companion wheel size and offset guide before choosing an aftermarket wheel.