Question 1

What is a Subaru chassis code?

Accepted Answer

A Subaru chassis code is the internal platform identifier Subaru uses to designate a specific generation. For example, VA refers to the fourth-generation WRX STI (2015-2021), GR refers to the third-generation hatch (2008-2014), and VB refers to the current WRX (2022-present). Subaru enthusiasts use chassis codes because they specify the exact platform underneath the car, which determines wheel fitment specifications including bolt pattern, offset, hub bore, and brake clearance.

Question 2

Do all Subaru WRX and STI models share the same wheel hardware?

Accepted Answer

Most modern WRX and STI variants share core hardware: 5x114.3 bolt pattern, 56.1mm center bore, and M12x1.25 lug nuts with 60° conical seats. However, OEM wheel sizes and offsets differ significantly by trim and year. The VA STI Base and Premium ran 18x8.5 ET55 while the Limited moved to 19x8.5 ET55 in 2018. The S209 limited edition used a unique 19x9 ET48 with wide-body fenders. The 56.1mm hub bore is smaller than most aftermarket wheel center bore standards (typically 73.1mm), so hub-centric rings are required for most aftermarket fitments.

Question 3

Does FMB Wheels build for the Subaru BRZ and Toyota GR86?

Accepted Answer

Yes. FMB Wheels builds custom forged monoblock wheels for both generations of the Subaru BRZ and Toyota GR86, which share the same Subaru-built chassis. Both the first-generation ZC6 (2013-2020) and the second-generation ZD8 (2022-present) are supported. The BRZ/GR86 uses a 5x100 bolt pattern (different from the WRX STI's 5x114.3) and 56.1mm center bore, so wheel selection follows separate criteria from the WRX STI lineup.

Question 4

Why is square setup mandatory on Subaru WRX and STI platforms?

Accepted Answer

All WRX and STI platforms are all-wheel drive with a center differential that requires consistent rolling circumference across all four wheels. Running staggered tire diameters or wheel widths stresses the center differential and can cause damage over time. All OEM WRX and STI configurations are square (front and rear identical), and aftermarket setups should follow the same approach. Tire wear should be matched across all four corners through regular rotation; replacing only two tires at a time on AWD Subarus creates rolling circumference mismatches that affect drivetrain operation.

Subaru Wheel Fitment

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WRX STI · VA (Final US Generation)

WRX STI · GR/GD (Classic)

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BRZ / GR86 (Joint Platform)

Forester XT / STI

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