Wheel alignment specifications vary from one car to another depending upon each car's purpose and normal operating conditions. Someone who uses his car primarily to commute in the city would likely drive a car with different alignment specifications than those of a car driven by someone who races off-road in rough conditions. Subaru's WRX is about as close as you can come to the latter and still be street legal and for sale on dealer lots in America. The WRX is an all-wheel-drive compact performance car manufactured by Subaru. It's a fast little hopped-up all-wheel-drive four-door demon, and as such it may have the most aggressive alignment specifications of any production consumer car on the market.
The factory recommended wheel alignment specifications for the Subaru WRX is as follow. The front right and left tire toe should be at zero and +/- 3mm. The front right and left tire camber should be set at zero, +/- zero degrees at three minutes. The rear right and left tire toe should be at zero and +/- 3 mm. The rear right and left tire camber should be -1.0 degrees and +/- zero degrees for 45 minutes. The WRX stock caster setting is approximately 3.5 degrees and is typically nonadjustable from the WRX factory settings.
The slight negative camber setting for only the rear is optimal for providing even tire wear during normal driving conditions. With the front and rear toe set at zero degrees it helps ensure solid, reliable handling as well as straight and even tracking. The zero front and rear toe setting is especially important for firm and straight driving at highway cruising speeds.
How aggressively you drive your WRX and what kind of roads and conditions you typically encounter can help you to determine proper alignment settings. More extreme or irregular driving conditions may call for slight alignment adjustments. For instance, for touring use, the WRX front right and left camber may be set at -1.0 degrees, and rear right and left toe may be set at 1mm toe-out. More significant alignment adjustments may call for aftermarket parts installation. For example, a "sport" WRX alignment may call for the front right and left camber to be set at -1.5 degrees and rear right and left camber to be set at -1.0 to -1.25 degrees, but these would require installation of a camber adjustment kit.
Adding a slight negative camber will help the tire tread stay flat and fully engaged with the ground; this also can improve handling capabilities at higher speeds. However, too much camber will reduce braking traction and acceleration traction, increase tramline (tire wandering in cracks and grooves) and crown sensitivity (tire wandering on road contour), and negatively influence tire wear, especially inner tire tread. Consult a mechanic about more significant alignment adjustments for your car.
Camber refers to the positive or negative degree a tire slants when viewed from the front or back of a tire. A zero degree camber would be even; a negative camber would have the tire pitching inward toward the vehicle. Toe refers to the angle of a tire being viewed from above. A negative toe will pitch inward toward the vehicle.
