T11-7-8 Countersinks (a) All webs shall be drilled and countersunk to properly fit the correct hub studs/nuts for the assembly being used. (b) The wheel must not prevent the wheel nuts from fully engaging their studs. (c) Wheels with slotted stud holes are not permitted. (d) The centre hole of the wheel web must fit the axle hub. (e) Centre webs of high tensile steel are not permitted T11-7-9 Offsets: Refer Diagram C
Any offset applied to the web of a wheel should not be more than 1/3 of the width of the inner flange of the rim. Any web of any wheel, whether offset or not, should be arranged such that, if not given additional strengthening as mentioned in T11-7-9 (10,11,12 below), both the outer diameter, where it welds to the rim, and the inner diameter, where it bolts to the hub, shall lie in the middle third of the width of the wheel. On any pressed centre the cross sectional inside radius of the curvature shall not be less than twice the thickness of the plate from which the web was pressed. On any saloon wheel centre web that is less than one third (1/3) of the total rim width from the outer edge of either side of the rim the centre web must be 10mm minimum thickness with 12.5mm minimum size wheel studs, except saloons fitted with 'wide 5' wheels where the centre web must be 8mm minimum thickness. All wheel stud spacers and wheel spacers are prohibited. Exception Halibrand type rear axles. Web Thickness For the type of wheel construction specified above, and subject to the constraints listed, the following thickness are minimums for class of cars listed hereunder: (ii) Super Saloon: Minimum 8mm (iii) For manufactured custom built and specialist production wheels using special pressing and/or alloy wheels; thicknesses may be less than the minimums above, but with an approved design certification required before use. Approved Wheels Clearly identifiable professionally manufactured wheels that are outside the above specifications may be submitted SNZ for testing and subsequent approval.
2010 ELECTRONIC RULEBOOK