Although changing ride height can affect alignment angles whether the height is raised or lowered, a condition that’s common with lowered cars is excessive negative camber. Camber is the tilt of the tire from vertical when looking from the front of the vehicle. When a car is lowered, the top of the tire leans in toward the center of the vehicle. This adversely affects handling and traction because the contact patch of the tires is reduced, and causes accelerated tire wear. A wheel alignment kit will allow camber to be adjusted to factory specifications.
The suspension on every vehicle has designed in wheel alignment angles that ensure safe, predictable handling and even tire wear. However, OE wheel alignment specifications assume that the vehicle is at or near the standard ride height. These specs can be thrown way off when a vehicle is purposely lowered or lifted for performance, and factory components may not provide the range of adjustment needed to correct angles altered due to the change in ride height.
Many of today's car alignment machines are equipped with printouts that compare the "before" and "after" alignment angles with the manufacturers' specifications. Requesting a post alignment printout can help you confirm the thoroughness of the car alignment technician and preserve a record of your vehicle's intended settings in the case of an encounter with a suspension damaging road hazard.
Your ride height will need to be precise for your vehicle to be in perfect working order. All these factors are designed to ensure ultimate handling, performance and overall driving experience. All alignment angles will be based off your ride (chassis) height.