Buying & Fitting New Alloy Wheels
There are numerous benefits to fitting alloy wheels to your car.
For a start they are cast from aluminium with means they are
light-weight, and more attractive than regular wheels. They are
great at dissipating brake heat and small amounts of more rigid
metals the presence of which helps prevent cracks propagating.
They are also available in standardised sizes, to fit almost
every car.
One of the best advantages of the wheels in performance terms,
is the reduction in your cars unsprung weight, meaning a
reduction in rotating mass at the ends of your suspension
components. This means improved steering and greater breaking
response.
For those who have not yet purchased those shiny new rims, these
definitions might go some way to clarifying the elaborate
specifications you will see when you're out shopping. When in
doubt, there are plenty of alloy dealers willing to lend their
expertise, and ensure you get a wheel that suits both you and
your car.
Offset - The offset is usually engraved on the wheel, and
means the distance between the wheel's centre-line and the hub
mounting face at the back of the wheel. Wheels with their
mounting face towards the front fact of the wheel are called
Positive Offset wheels. Most front wheel drives are this kind.
Wheels that have their mounting face level with the centreline
of the wheel are called Zero Offset wheels. You can guess
therefore, that wheels with their mounting face towards the rear
of the wheel are called Negative Offset wheels.
PDC - This stands for Pitch Circle Diameter. It measures
the diameter of the circle drawn through the centre of the bolt
holes of your wheels. It is measures in millimetres and will
often help you ascertain how many studs or bolts the wheel will
have.
Centrebore - This is the size of the hole at the back of
the wheel into which the hub fits. This hole needs to match the
size of the hub exactly, in order for the wheels to seat
properly. Most modern wheels are referred to as 'hub-centric' -
meaning the hub is 'load-bearing'. This means that all the bolts
or studs do is hold the wheel onto the hub. 'Lug-centric' wheels
imply that you bolts or studs have a more critical job, so you
need to ensure you check and tighten them regularly.
Up-Stepping - This relates to the practise of increasing
your wheel-diameter and reducing the profile of your tyres. This
can increase the handling of your car, response and feedback.
When fitting new alloys, initially you must ensure you have the
right kinds of bolts, as they have various diameters, threads
and seatings - something that your wheel supplier will be able
to advise on. It is normally recommended that you get a
professional fitter to do the job for you anyway, so buying your
wheels from a dealer willing and qualified to fit them is a good
idea. If you spend money on a quality pair of wheels, have them
professionally fitted and keep on top of the grime and damage
regularly - your alloy wheels will repay you by lasting a lot
longer than you would expect and will look a good deal shinier
too.