• Apex. The center point of an arc. As part of a driving line, this point is approached from the outside of an arc (turn-in) and lies closest to the inside edge of the track.
  
  
  • Early Apex. Turning into a corner, from turn-in, to drive an arc that places the car at the inside of the track before the geometric apex (exact center of the arc), which would carry the car off-track if it were to maintain this arc and speed through the entire curve. In order to stay on-track, the driver typically needs to adjust speed or the radius of the arc, or both, sacrificing exit speed. useful in sustaining speed for the longest period when entering the first corner following a straight line (type 2 turn). Also useful in extending one's brake-zone as needed or as a competitive placement tactic.
    
    
  • Late Apex. Transition through a curve, placing the car at an apex that occurs after the geometric apex, or center of the arc. Such placement allows the car to drive a wider radius are (increasing radius) with commensurate increase in speed upon exit, or track-out.
    
    
• Armco. Metal barrier or guard rail.
  
  
• Braking Point. The point on track at which the brakes are first applied.
  
  
• Confidence Lift. Briefly lifting off the throttle at the entrance of a turn, usually with the intent to slow the car enough to restore confidence that the driver will, in fact, be able to execute the turn.
  
  
• Contact Patch. Area of tire surface in contact with the road surface.
  
  
• Curbing. Raised, often ridged surfaces flanking the track intended to maintain the integrity of the track edge and remind drivers that they've reached the edge of the track surface. A.k.a. Rumble Strips, Gators, Dragon's Teeth, Berm).
  
  
• Drift. Transition through a turn with all four tires in a controlled slide, balancing over and understeer conditions with application of brake, throttle, and steering controls.
  
  
• Flat Spots. Area of tire tread worn to a point beyond tread depth, often showing wear bars or cord, created by sliding or brake lock-up.
  
  
• Friction Circle. A circle graph describing your vehicle's maximum traction before it looses grip. Finding and maintaining these traction limits are the key to carrying maximum speed around the track. Click here for to view a friction circle diagram.
  
  
• Grid. As you prepare to go on track, you will advance your car to the grid, which is a designated area to line up with the rest of the drivers until the pit martial releases your group on track.
  
  
• Line. Path described by tghe movement of a vehicle through a curve or series of curves and straight sections of road or track. While describing the line through a corner, one begins at turn-in, the to an apes, exiting at track-out.
  
  
  • The Line (a.k.a. School Line in HPDE). Path around entire track, described by turn-in, apex, and track-out points at all corners. This driving path potentially yields the highest levels of control, smoothness, balance, predictability, and safety when practiced and executed with consistancy.
    
    
  • Race Line. Desired path around track or through a section of track that is not currently occupied by a competitor's vehicle.
    
    
• Loading/Corner Loading. Modifying the 'apparent' weight applied to one or more tires (and associated suspension getmetry), through application of various controls (steering, brake, throttle) to maximize grip and/or affect of those tires.
  
  
• Marbles. Small chunks or rubber, formed as liquefied tire rubber separates from the tire cooling to solid form as it tumbles in the air and on the track surface. Settling on the outside of a corner, these may cause loss of traction if one drives though an area of track where many of these have accumulated.
  
  
• Red Mist. Aggressive driving attitude demonstrated by drivers whose enthusiasm overcomes their common sense.
  
  
• Oversteer. Tendance of the car to turn into the center of a curve, shortening the radius of the curve driven by the steering wheels, and increasing the curve driven by the rear wheels. A.k.a. Loose.
  
  
  • Power Oversteer. Oversteer condition induced by the increased application of throttle (rear wheel drive vehicles), as one executes a turn, following turn-in. This action may break traction at the rear wheels, causing the rear of the car to describe a longer radius arc, pointing the vehicle towards the inside of the turn.
    
    
  • Trailing Throttle Oversteer/Lift Throttle Oversteer. Oversteer induced by application of the throttle while turning into a curve, and after what would normally be the "brake zone", then lifting off throttle beyond entry to a turn. This effectively unload the rear wheels, causing these to break traction and slide the rear of the car into a longer radius arc. Unintentional LTO typically results in a spin. Effective application of LTO will reposition the car by changing trajectory, creatign a shorter radius arc throughout the remainder of the corner, allowing steering input to be reduced before track-out.
    
    
• Pit In. Process by which you exit the racing surface and return to the pit area. This should always be preceeded with holding up your fist out the window to inform other drivers of your intent to leave the track.
  
  
• Pit Out. Process by which you exit the pit area or grid as you enter the racing surface. Always make sure the pit marshall has given you clearance to enter the track and make sure to check your mirrors before moving out in the main portion of the course. Many tracks will also recommend staying all the way to the inside of the track around the first corner to help ensure you are not pulling directly into high speed traffic.
  
  
• Rotating The Car. Technique for getting the car to turn quicker (Trail Braking, Lift Throttle Oversteer, Throttle Steering).
  
  
• Short Shifting. Up-shifting at a lower RPM than typical shift points which occur at or just below torque peak.
  
  
• Slide. Reduced traction at one or more contact patches, allowing maintenance of control and increased acceleration while slightly sliding toward the outside of a turn.
  
  
• Slip Angle. Angle described by the direction of travel and direction of the steering wheels as a vehicle changes direction. Using steering inputs and speeds that maintain this angle (or less than maximum slip angle) permit steering control and acceleration. Exceeding this maximum angle results in reduction (or elimination) of traction, control, and speed.
  
  
• Straight. Any portion of the track that is not curved. As you develop your driving skills, you will begin to look at the track (and it's corners) and a series of connected 'straights'. As you begin to use these 'straights' to your advantage, you will be able to carry more speed around the track.
  
  
• Throttle Steering. Using throttle application to modify the trajectory, and thus the line, through a turn to induce oversteer, understeer, or reset balance with intent to drive the desired line.
  
  
• Track-Out. Point on track, at the end or a turn, where the driver exits the corner.
  
  
• Trail Braking. Carrying braking into (typically) the first third of a turn, with the purpose of extending the braking zone and/or loading the steering wheels. Proper execution requires diminishing brake-pedal pressure as steering is increased. Similar results are achieved by lifting off throttle while transitioning into a turn.
  
  
• Turn. Any portion of your line on track that is not straight.
  
  
• Turn In. Point on track, at tnery to a turn, where the driver first applies steering.
  
  
• Turn Radius. The radius of the course that you take through a turn. A larger radius will allow you to carry more speed through the turn and exit into the next straight at a faster speed.
  
  
• Threshold Braking. Maximum braking capacity of a vehicle under the control of the driver. Attempting to decrease speed by increasing brake application beyond this threshold point will cause the brakes to lock or freeze one or all of the wheels, resulting in loss of traction and, subsequently, control of brakes and directioni of travel.
  
  
• Understeer. Tendancy of the car to drive straight rather than turning into a curve, increasing the radius described by the front/steering wheels as these tires lose traction. Corrective actions may include reducing steering input (straighten the wheel) to allow speed reduction, momentary braking, or both (conducted in that order) to facilitate increased traction. A.k.a. Push, Plow, Tight.