the following is taken from here
http://www.transport.qld.gov.au/resourc ... icles2.pdf
happy reading.
The rim diameter may be varied from the standard size
but the overall diameter of the tyre must not vary by
more than +15mm or -26mm.
The tyres must have a tread depth of at least 1.5mm on
every part of the tyre that touches the road and not have
any apparent defect that is likely to make the vehicle to
which they are fitted unsafe. It is not permitted to fit
tyres that have been treated by recutting or regrooving
unless the tyre has been marked by the original
manufacturer as ‘suitable for recutting or regrooving’.
The maximum tyre width for a car or car derivative must
not be more than 1.3 times the vehicle manufacturer’s
widest optional tyre.
However, for an off-road passenger vehicle fitted with
front and rear beam axles, the maximum tyre width
must not be more than 1.5 times the vehicle
manufacturer’s widest optional tyre.
The nominal width of the narrowest tyre fitted to a
vehicle must not be less than 70 per cent of the nominal
width of the largest tyre fitted and never less than the
vehicle manufacturer’s narrowest optional tyre as
indicated on the manufacturer’s tyre placard.
The rims and tyres must not protrude beyond the
bodywork of the vehicle, including flares, when viewed
from above with the wheels facing straight ahead. If the
vehicle was originally constructed with a portion of the
wheel protruding, the wheels must not protrude further
than originally constructed.
Speed and load ratings
The speed rating of all tyres must be:
• a speed of at least:
for an off-road passenger vehicle – 140km/h
for another car (sedan, station wagon etc.)
up to nine adult seating positions or a car
derivative – 180km/h
for another motor vehicle – 120km/h
• the vehicle’s top speed, if lower.
Load ratings of tyres must be at least equal to those
specified by the manufacturer on the tyre placard fitted
to vehicles made after 1972. For other vehicles, the load
rating of a tyre must be capable of carrying the part of
the vehicle’s gross mass carried by the tyre.
Vehicle track
Track is measured at ground level from the centre of the
tyre on one side to the centre of the corresponding tyre
on the opposite side of the vehicle. Front and rear track
differs on many vehicles.
The wheel track must not be reduced to less than the
standard track specified by the vehicle manufacturer
for the particular model of vehicle.
The track of a car or car derivative may be increased
by up to 26mm beyond the maximum specified by
the vehicle manufacturer for the particular model of
vehicle. Off-road passenger vehicles fitted with front
and rear beam axles, may have an increase in track
up to 50mm beyond the maximum specified by
the vehicle manufacturer for the particular model
of vehicle.
Repairs to tubeless tyres
Permanent repairs can only be made when the tyre is
removed from the rim. The tyre must be examined to
ensure it is structurally sound. The damaged area must
be prepared on the inside for a patch or mushroom
headed plug to be fitted and vulcanised into position.
Any repairs to a tyre must be sealed to prevent moisture
or contaminants from entering the tyre casing or
structure.
Caution: Plug repairs can only be made in the tread area
of the tyre and not in sidewalls or where the tread and
sidewall meet.
Punctures in tubeless tyres must not be repaired from the
outside or without removing the tyre from the rim as
this method is prone to failure.
Vehicle owners with doubts on tyre repairs should
contact a reputable tyre dealer for proper repairs.
Tyre construction
Tyre tread compounds, patterns, ply ratings and
performance characteristics vary. Tyre construction
(e.g. radial) and size must be the same on the same
axle. Although it is recommended that the tyres are
identical (e.g. same brand and tread pattern), this is
not mandatory.
The fitting of spacers or adaptors between wheels and
hubs, additional to those provided by the vehicle
manufacturer, is not permitted. The tyre and rim must
not foul wheel arches or suspension components under
any conditions. Steering limit stops must not be adjusted
to reduce the turning circle in order to allow the fitting
of the alternative rims and tyres.