Offset means what?

Offset is normally stamped or engraved into the wheel and is measured in millimeters of ET: ET is the short form of the German word Einpresstiefe which translates as insertion depth.

Offset is the distance between the hub mounting face at the back of the wheel and the wheel's centerline.

Negative Offset wheels have their mounting face toward the rear of the wheel - powerful rear-wheel drive cars often have wheels with negative offset.

Zero Offset wheels have their mounting face even with the centerline of the wheel and are by definition ET0.

Positive Offset wheels have their mounting face toward the front face of the wheel. Front wheel drive vehicles usually have positive ET wheels. Eighties & Nineties Volkswagen wheels are generally ET38.

PCD means what?

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 indicate the number of studs or bolts the wheel will have. Volkswagen Alloy Wheels are usually either 4x100: i.e. 4 bolt holes drilled through the centre of an imaginary 100mm circle, or 5x100: for VR6s, GTis and MK4s.

Center bore means what?

The center bore 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 what's called hub-centric. This means that the hub which protrudes from your car, and mates with the equivalent sized hole at the back of your wheel, is load bearing. All that the studs or bolts do is holding the wheel onto the hub.

If you have lug-centric wheels, the state of your studs or bolts is obviously more important - be sure to replace these from time to time and always 3/4 tighten the wheels off the car to make sure they're centered.

Plus-Sizing and Up-Stepping means what?

Plus-Sizing or Up-Stepping are two terms given to the practice of rising the diameter of your wheels whilst at the same time reducing the profile of your tires to keep the overall rolling radius the same.

Benefits
Plus-Sizing will develop the handling of your car! Each step will decrease the proportion of flexible tire sidewall to rigid alloy. This will improve response, will help keep the tire tread square to the road and will improve your car's feedback. If done correctly speed and odometer accuracy will retain and the car look better.

Disadvantages
Often, tire inches are lighter than wheel inches. Plus-sizing can make your overall wheel/tire package heavier. Reducing the profile of your tires will also decrease your car's damping deflection under compression the ride quality will get worse. Other disadvantages can include the need for more expensive tires, your brakes looking undersized and people's grannies laughing and calling your car a buggy.

You got the Alloy Wheels and then what?

Before you do anything, ensure to see that you have the right sort of bolts - Bolts and studs have various diameters, threads and settings, your wheel supplier should be able to advice on this. Also check to see that you the 4 plastic spigot rings which help the interface between the wheel and the hub.

Next you need to jack your car up; do this in a secure way, and be sure to use axle stands, chock wheels still in contact with the ground and apply the parking brake. Offer a wheel up to the car and check that the bolt holes line up, that the wheel locates on the hub properly and that there is wheel arch, suspension strut and brake caliper clearance. If you have upgraded your brakes be SURE to seek advice and measure everything thoroughly before you order.

The wheel bolts or nuts must be tightened to the manufacturer's precise torque. Be sure to re-torque after a 100 miles or so as they will compress slightly; tighten them increasingly till they're 3/4 tight then lower the car and complete the process.

Take care of your Alloy Wheels

As anybody who's stepped into a motor factor in the last 10 years will tell you, there's a huge variety of specialist wheel cleaners on the market, all designed to help make the job of cleaning your new rims that little bit easier, unfortunately the real key to a great finish is hard work.

Before you fit your wheels, give them several coats of good quality car polish back and front. This will help prevent the road salt, brake dust and dirt keying to the surface on first use. Be sure to treat the surface of your alloys as well, if not better, than you would your paintwork. Remember, you have spent a small fortune of your alloys and they're going to be subject to the harshest conditions of just about any part of the car!

Frequent washing with mildly soapy warm water; and remember to hose all the loose abrasive grit off first. This is the best way to keep wheels clean. Do not use abrasive cleansers, electric buffers or wire wool pads on your wheels. Where it is possible let your wheels cool before cleaning them and keep away from car-wash wheel-cleaners at all times.