What is Offset?
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.
What is PCD?
PCD stands for pitch circle diameter and is the diameter of a circle drawn through the center 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 center of an imaginary 100mm circle, or 5x100: for VR6s, GTis and MK4s.
What is Center Bore ?
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 ?
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 response. If done correctly speed and odometer will retain its accuracy .
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. Other disadvantages can include the need for more expensive tires, and your brakes looking undersized.
Installing your new wheels?
Before anything, ensure that you have the right sort of bolts - Bolts and studs have various diameters, threads and settings, Not to worry , Readywheels will provide you with the correct install kit. Also make sure you have the 4 plastic spigot rings which help the interface between the wheel and the hub.
Next 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 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.
We offer specialty wheel cleaners made specifically for your new wheels , all designed to help make the job of cleaning your new wheels easier.
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 wheels and they're going to be subject to the harshest conditions of your car!
Frequent washing with mild soapy water; and remember to hose all the loose abrasives 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