The size of the tyre
you’re fi tting will
have a direct impact
on the offset you
need to runWHAT OFFSET
SHOULD I RUN?
The $64,000 question! The
short answer is there is no
short answer, because every
vehicle is different. Generally
speaking, if you’re fi tting a set
of tyres up to 2inches larger
than standard diameter, then
look for a wheel that increases
your negative offset
somewhere in the realm of
15-30mm. Start by googling
your vehicle’s factory offset –
type in, for instance, 2016 Isuzu
D-MA X wheel offset to fi nd it
has an offset of positive 35mm.
Knowing that we want to
increase the vehicle’s wheel
track/width, you’d want to look
for a wheel that has something
between a zero and +10mm
offset. This will give the vehicle
a wider stance, allow for the
fi tment of bigger tyres as we
spoke about earlier, and keep
the tyres mostly inside the
guards. If you’ve got an older
solid-axle 4WD and are looking
to step up to a set of 35inch
tyres, you’d likely want to look
for something that increases
the wheel track at least
30-45mm, to something like a
-44mm rim. However this then
brings with it substantial legal
issues, which need addressing.LEGALITIES
So here’s the rub. Australian
Design Rules state that to
comply with ADR 24, a
vehicle’s wheel track may
only be increased by a
maximum of 25mm. In reality
many 4WDs are already
exceeding this amount and
it’s up to each individual
owner to decide whether or
not they want to take the risk
of running foul of the law.
Highway Patrol and roads
departments typically have a
hard-on for overall tyre
diameter and tyre width
rather than wheel track, but it
all goes hand in hand.
Keeping tyres within the
confines of your guards is
vitally important, as it is
definitely illegal for the outer
edges of your tyres to stick
outside the guards. You can
fix this either by fitting rubber
guard extensions or by fitting
wider replacement wheel
arch flares from any number
of manufacturers who make
them these days. Note that
this won’t fix your issues with
wheel track, but it will go a
long way to keeping your rig
looking a lot more
respectable and out of the
spotlight of highway patrol
looking to fill quotas.USING OFFSET
TO FIT BIGGER
TYRES
The most common reason to
increase wheel track with
larger negative offset rims is
to fit bigger, wider tyres.
Fitting wider tyres can cause
clearance issues with
steering and suspension
arms, particularly in the front
of the vehicle, and with the
inner guard in the rear of the
vehicle on full up-travel. By
fitting wheels with an
increased negative offset, you
push the tyre’s positioning
slightly outwards and away
from the inside of the vehicle.
However be aware that
pushing it too far outwards
will often result in the tyre
making contact with either the
guard or the wheel arch on
full up-travel, with damage
from the tyres being a
common occurrence.
INCREASING
WHEEL
OFFSET
Here’s where the terminology
gets a little confusing. We as
4WDers generally use the term
‘increased wheel offset’ when
referring to wheels with a
greater negative offset than
standard. Technically a more
correct term would be
‘increased wheel track’, which
is the overall distance between
the outer edges of two wheels
on the same axle. Increasing
offset, in 4WD terms, generally
means increasing the amount
of negative offset a wheel has.
The wider a vehicle’s wheel
track, the more stable it is, and
the more capable it is too, as it
has the ability to fi nd more
traction in tricky off-road
situations. Most 4WDers fi t
wheels with a larger negative
offset as a way of increasing
the vehicle’s off-road ability.WHEEL OFFSET EXPLAINEDTECH TALK
WWW.4WDACTION.COM.AULarge offset
wheels will need to
be covered in some
way. Extra-wide
fl ares have been
fi tted to this 80
Series to keep the
wheels coveredV8 70 Series Cruisers run a narrower
rear diff than the front. One way to fi x
this and bring the front and rear wheel
tracks into alignment is to run wider,
more negatively-offset rims in the rear