WHAT IS AN ALLOY WHEEL?
In the past 5-8 years, manufacturers have increasingly fitted alloy wheels to their passenger cars. Prior to this, manufacturers almost always used steel wheels. Steel wheels are more resilient to damage, and are considerably cheaper to fit. However, they are almost always heavier, less attractive and smaller in both diameter and width than alloy wheels. We offer both as a solution to the wheel conundrum. Often, customers choose to have Steel Wheels for winter use, and alloy wheels for summer use.
The term “alloy wheels” is usually given to wheels ‘cast’ from a mixture of aluminium and other materials. Aluminium is light-weight and great at dissipating heat. The smaller amounts of other, more rigid metals in the ‘alloy’ provides rigidity and helps prevent cracks propagating.
WHAT ARE THE BENEFITS OF FITTING ALLOY WHEELS?
In general, our alloy wheels are lighter, more attractive, and better at dissipating brake heat that their steel counterparts. We supply them in standardised sizes and in a wide range of fitments.
Fitting alloy wheels often reduces your car’s unsprung weight (particularly if you choose our lightweight “track inspired” range) – this means a reduction in rotating mass at the ends of your suspension components, giving you improved steering feel and greater braking response.
WHAT DOES PCD MEAN?
PCD stands for ‘pitch circle diameter’ and is the diameter of a circle drawn through the centre of your wheel’s bolt holes. P.C.D. is measured in millimeters and also indicates the number of studs or bolts the wheel will have. Many European cars, such as Peugeot and Citroen are 4×108 (i.e. 4 bolt holes drilled through the centre of an imaginary 100mm circle), whereas some such as Volkswagen and Audi are often 5×100. Typically, Japanese cars are often 5×114.
WHAT DOES OFFSET MEAN?
Offset is the distance between the hub mounting face at the back of the wheel and the wheel’s centreline. The offset is usually stamped or engraved into the wheel and is measured in millimetres of ‘ET’ (ET is the short form of the German word ‘Einpresstiefe’ which literally translates as ‘insertion depth’)
Positive Offset wheels have their mounting face toward the front face of the wheel. Most front wheel drive vehicles have positive ET wheels. For example, 1980s and 1990s Volkswagen wheels are usually ET38.
Zero Offset wheels have their mounting face even with the centerline of the wheel and are by definition “ET 0”.
Negative Offset wheels have their mounting face toward the rear of the wheel – powerful rear-wheel drive cars often have wheels with negative offset.
WHAT DOES CENTRE-BORE MEAN?
The ‘centerbore’ of an alloy wheel is the size of the hole at the back of the wheel which the ‘hub’ fits into. To help the wheels to seat properly this hole needs to be an exact match to the size of the hub.
Most modern wheels are ‘hub-centric’, which means that the hub which protrudes from the vehicle (and mates with the equivalent sized hole at the back of your wheel) is ‘load bearing’. All the studs or bolts do, therefore, is hold the wheel onto the hub.
If you have ‘lug-centric’ wheels, the state of your studs or bolts is obviously more critical – in this scenario, always 3/4 tighten the wheels off the car to ensure they’re centred.
WHAT IS UP-STEPPING / PLUS-SIZING?
Up-Stepping and Plus-Sizing are two terms given to the practice of increasing the diameter of your wheels whilst simultaneously reducing the profile of your tyres to keep the overall rolling radius the same.
There are benefits to this: Plus-Sizing will often improve the handling of your car, as each step will reduce the proportion of flexible tyre ‘sidewall’ to rigid alloy. This should also improve responsiveness, keeping the tyre tread square to the road and improving your car’s ‘feedback’. If done properly speedo and odometer accuracy will be retained, whilst ensuring the aesthetic benefits are still valid.
HOW DO I FIT AND CARE FOR MY ALLOY WHEELS?
Advice on Fitting and Wheel care can be found in our Knowledge Base