MOD/CHECK

NSW wheels & tyres guide

Wheels &
tyres.

Choose the right reference, understand the dimensional result and keep load, speed and fitment checks in view.

Open basic tyre check →Comprehensive assessment →

NSW light passenger & commercial vehicles ≤ 4.5 t GVM
Guide reviewed 3 October 2026 · VSI 06 Rev. 4

Read a metric tyre size

265/70R17: width, aspect ratio and rim diameter 265 is nominal section width in millimetres. 70 is sidewall height as a percentage of width. R means radial construction. 17 is rim diameter in inches. 265 / 70 R 17 265Section width · mm 70Aspect ratio · % 17Rim diameter · inches
R means radial construction. Tyre section width and wheel-rim width are different measurements.

01 · Prepare your information

One vehicle can have different references.

Start with the applicable Road Vehicle Descriptor (RVD), tyre placard and manufacturer specifications for the vehicle variant. Keep a photograph or copy with your assessment record.

Diameter reference
The largest-diameter manufacturer-listed tyre.
Tyre-width reference
The widest manufacturer-listed tyre. It may be a different option from the diameter reference.
Rim-width reference
The greatest applicable manufacturer-listed rim width. Enter the fitted rim width separately, in the selected units.

An earlier tyre change does not become the manufacturer reference. Enter front and rear fitments separately when the selected comprehensive or combined workflow asks for them.

02 · Understand the dimensional result

Diameter and width are separate triggers.

VSI 06 · Item 15

Overall diameter

A change greater than 7% from the largest specified diameter indicates the dimensional certification pathway. The change can be an increase or a decrease. Speedometer compliance is a separate part of Item 15.

Diameter change(Fitted diameter − reference diameter)
÷ reference diameter × 100

For a metric tyre, nominal diameter in millimetres is twice the section width multiplied by its aspect ratio, plus rim diameter in inches multiplied by 25.4.

VSI 06 · Item 16

Tyre or rim width

An increase greater than 25.4 mm (1 inch) above the applicable manufacturer maximum indicates the current width pathway. Compare tyre width and rim width independently.

Width increaseFitted width − manufacturer maximum

Exactly 7% or exactly 25.4 mm does not exceed the respective dimensional trigger. This does not establish overall compliance. Item 16 was amended from 1 July 2026; enter the actual completion timing when asked.

03 · Check the rest of the combination

A size result does not settle the ratings.

Load evidence

Record the manufacturer’s minimum load specification, tyre load index, required tyre category and wheel load rating. The comprehensive workflow also asks for axle-load evidence and any changed vehicle mass ratings.

Item 17 concerns combinations that do not meet the manufacturer’s minimum load capacity. A tyre size alone cannot establish this. A higher number on the sidewall does not prove the wheel is adequate or the required tyre category is retained.

Speed rating

Record the build date, vehicle class, fitted and manufacturer ratings, and vehicle top speed where required. The mandatory minimum is assessed under Schedule 2 rule 50, which has its own applicability and exceptions.

A lower-than-placard rating can meet that minimum. VSI 09 recommends a driver-visible warning label in that situation; MOD/CHECK records this as advice. A rating below the mandatory minimum requires rectification. Missing evidence remains a review outcome.

04 · Worked examples

Read each comparison on its own.

Hypothetical manufacturer options, not specifications for a particular vehicle. The examples use 265/70R17 as the largest-diameter reference and 285/60R18 as the widest tyre reference. Assume the current width pathway applies to a modification proposed or completed on/after 1 July 2026.

Within dimensional thresholds

305/65R17 fitted

Reference diameter
802.8 mm
Fitted diameter
828.3 mm
Diameter change
+3.18%
Tyre-width increase
+20 mm

Neither tyre-size trigger is exceeded. The remaining wheel, tyre and vehicle requirements still apply.

Width certification indicated

33×12.50R17 fitted

Fitted diameter
838.2 mm
Diameter change
+4.41%
Fitted section width
317.5 mm
Tyre-width increase
+32.5 mm

The diameter change stays within 7%, but the width increase exceeds 25.4 mm. These are independent results under the current pathway.

Diameter certification indicated

245/60R17 fitted

Fitted diameter
725.8 mm
Diameter change
−9.59%
Tyre-width change
−40 mm

The diameter decrease exceeds 7%. A narrower tyre does not cancel the diameter finding.

Choose your assessment

Start with the scope you need.

Basic tyre check

Compare nominal tyre diameter and tyre width with the two manufacturer references.

Open basic check →

Comprehensive wheels & tyres

Add guided rim-width, load, category, speed-rating and speedometer checks.

Open full check →

Wheels + suspension

Assess the interacting changes and their combined nominal effect on vehicle height.

Open combined check →

Official sources

Check the source behind the finding.

Guide reviewed 3 October 2026. Individual calculator findings retain their own source review dates. Read older guidance alongside the current Declaration Order and applicable vehicle standards.

Changing more than the wheels?

Use Inspection Mode to record all relevant live systems in one assessment.

Open Inspection Mode →Suspension & ride height guide →Engine & performance guide →Understanding your result & VSCCS →View all guides →