Important Modification Tips: Understanding Wheel Fitment

• Explanation: The distance from the center of the wheel to the mounting surface of the wheel hub. This directly determines the overall position of the wheel in relation to the fender, and the suspension assembly.
  
  
• Offset Types:

1. Positive Offset : Mounts closer to the outer edge (fender side) of the wheel.
2. Negative Offset : Mounts closer to the inner edge (suspension side) of the wheel
   
   

• Examples: (Note: Offset is measured in +/- millimeters, where 25.4mm = 1”)

1. An 18x10 +0 wheel mounts exactly 5” in, at the center line to the wheel.
2. An 18x10 +25 wheel mounts exactly 4” in, moving the wheel 1” (25.4mm) closer to the suspension
3. An 18x10 -25 wheel mounts exactly 6” in, moving the wheel 1” (25.4mm) closer to the fender
   
   

• Important Points to Consider: Offset is directly related to the width of the wheel. Two wheels with the same offset, and different widths will be positioned differently on the same vehicle.

• Explanation: When changing the width and offset of our wheel specs, we need to think about how this is going to affect both the fender side, and suspension side of the vehicle. Additional width with the same offset as the previous wheel set is simply divided in half for the inner and outer. After we have calculated this, we can then add (or subtract) offset accordingly.
  
  
• Examples:

1. Same Offset: If the factory wheel is 18x8.5 +53, compared to an aftermarket 18x9.5 +53, there is a 25.4mm difference in width. The new wheels will be 12.7mm closer to the fender, and 12.7mm closer to the suspension.
2. Different Offset, Different Width: If the factory wheel is 18x8.5 +53, compared to an aftermarket 18x9.5 +38: There is a 25.4mm difference in width. There is a 15mm difference in offset (closer to the centerline of the wheel). In this instance, we will take the 12.7mm in additional width, add the 15mm difference in offset and add them together: This wheel will be 27.7mm closer to the fender. We will now use the same train of thought on the suspension side of the wheel. While the extra width gives us 12.7mm closer to the suspension, the 15mm of offset will make this wheel 2.3mm farther away from the suspension compared to the OEM wheel.
   
   

• Important Points to Consider: Overall design of the face of the wheel may be impacted by the width and offset of the wheel. Oftentimes, wheels with aggressive width and offset will have clearance for big brake kits, more concave features to the face, or a bigger lip depending on the design of the wheel.

• Ride Height:
  
  
• When a vehicle is lower than stock, it may increase the difficulty to fit wheels that are wider than stock, or have a lower offset.
• A lowered vehicle may require a wider or lower offset wheel for a flush fitment, but a higher ride height may result in the same wheel extending outside the fenders.
  
  
• Tire Size:
  
  
• In most cases, tire size is recommended to increase as the width of the wheel increases.
• Tire size will directly relate to the fender clearance at ride height, as well as the turn radius
  
  

• Alignment:
  
  
• Subaru factory adjustment points allow approximately one degree in either direction.
• A lower offset and wider wheel may require aftermarket suspension arms for proper alignment ranges.
• Camber, Caster, And Toe directly impacts the location of the wheel when it is installed on a vehicle, and these values may help or harm the amount of tire / wheel clearance of your vehicle.
  
  Again, every vehicle, driver configuration, and the set of performance goals for the enthusiast are different. Proper understanding of the measurements, calculations, and specifications are critical to ensure that the enthusiast gains proper performance, desired stance, and a safe ride while remaining confident that their vehicle has been modified appropriately.

Do you need some new wheels?

You are looking in the right place. The Subimods online catalog contains a large selection of wheels, aftermarket parts, components, and accessories that can help your upgrade or modification move in the right direction. Subimods offers a number of solutions from some of today's best manufacturers. 

Our experienced team is here to guide you, so contact us today with your questions and we will do all we can to help you start your modification journey the right way. 

Check out the product rotator below with some amazing wheel options to hopefully get you started on your journey. 

We would be very interested in your thoughts regarding this article and would encourage your feedback and comments regarding Subaru's newest offerings. It doesn't matter if you have had your Subaru for decades or months, we have something for everyone here at Subimods. 

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