Whether you think wheels and a drop constitute a build or not, realistically, proper fitment on excellent wheels and your choice of lowering methods make a car completely different. A lowered height, good wheel choice, and proper wheel fitment drastically improves the look of a car and can take it from boring commuter to enthusiast vehicle, regardless of what the car is. If all you want to do is improve the look of your car with a bit of a personal touch to show your enthusiasm for whatever you drive, this is the way to do it. All you need is the information to make those mods and do it right the first time. That’s why today we’re going to explain what you need to know about wheels, fitment, spacers, and more to get the perfect look for your Audi, BMW, MINI, or Volkswagen.
What is Fitment?
Fitment is easy but it does take some math. To understand fitment, you need to understand wheel sizing. Wheels are measured with a diameter, width, and offset. They are, of course, bolt pattern and center bore specific, but we’ll cover that in a bit. Your fitment is mostly determined by offset, which is just how far inboard or outboard your mounting face is from the center of the wheel. For instance, if you have an 8-inch wheel width, with an offset of 0 (et0), then your wheel has exactly four inches inboard and four inches outboard. Offset is either positive (+) or negative (-), which tells you where your mounting face sits. Positive means it sits however many millimeters outboard from the center, negative is how many millimeters inboard. A wheel with an et30 is 30mm out from the center, a wheel with et-30 is 30mm inboard from the center.
Fitment generally refers to where the wheel lip sits with the body. A ‘flush’ fitment will have your fender and wheel in line with each other. Aggressive fitment usually means the wheel pokes out a bit, generally cambered, where the wheel and tire sit away from the body. A mild fitment, like a tuck, has the wheel just inside the fender so that it tucks inside the wheel well when lowered. To measure before you buy wheels to see what fitment you need, you will want to measure the distance from your wheel hub face to the edge of the fender well and note that difference. If it is, for instance, 3 inches, you will want your wheel to have three inches from the mounting surface to the wheel to be flush. So a flush fitment with a 17×8 would be an offset of et25, or 2.5cm, or 25mm, which would mean your wheel would have roughly 3 inches on the outboard side from the mounting surface and 5 inches inboard. This is an example, but all you need to know is that the offset is mm from the center, which tells you how much you need to account for when searching for wheels.
If you have wheels that are not as aggressive as you want, but like the wheels, another way to achieve the offset you want is to use spacers. Spacers mount in between the wheel and hub, which pushes your wheel out farther, and mimics a lower offset. If you need another inch to make your wheels ‘flush’ with your fenders, then a 25mm spacer would give you the fitment you want. For instance, if your wheel is et40, with 25mm spacers, your wheels would look like they were et15.
Ideally, your wheels have the correct center bore for your hub, as should any spacers you choose to run. This is critical since the center bore is designed to center the wheel and keep it from wobbling. If your center bore is bigger than your hub bore, you NEED hub-centric rings to mount the wheels safely. While they will bolt up, without hub-centric rings, you may find your car shakes at specific speeds which mimics an imbalanced or bent wheel. You should, however, aim to have hub-centric wheels with hub-centric spacers if you need to add spacers.
Wheels have a bolt pattern, or PCD, that tells you how far each bolt hole is apart from each other. The PCD is generally written as 5×120, which means 5 lugs, 120mm spacing. BMWs use 4×100 in some old cars, 5×120 in most new cars, and some other spacing that is uncommon. VW usually uses 4×100, 5×100, and 5×112, as does Audi. Porsche is 5×130. Your wheels need to have the correct PCD or they will not mount on your car. Ensure you purchase wheels with the correct PCD unless you plan on using adapters. Adapters are a perfect way to give your car different wheels that wouldn’t otherwise work, like using a 4×100>5×100 adapter on an E30 to run VW wheels.
With all this information, you should have everything you need to measure and purchase wheels or spacers that fit your car perfectly. Of course, you can find wheels, suspension, spacers, hub-centric rings, and lug nuts right here at ECS Tuning. Armed with the knowledge to achieve your perfect fitment, you can make the educated choice and do it right the first time.