Tire and Traction Seminar Kevin Katzenberg Race Car Builder / Wild Inc. Working on Race Cars for 24 years Turk Letizia Dirt Late Model Driver 12 Years
Things I ve Learned Don t Ever Stop Learning! There is always an exception to every rule. Take everything you learn and take it to the core of understanding. If anyone says you need such and such to win races; DON T BELIEVE THEM! (see item#2)
Tires and Traction
Tire Construction
Three Basic Types of Friction Adhesion: Like tape; Molecular bonding; Works best when tires are up to temperature Deformation: Conforms to the shapes in the road surface; Softer tires work the best as long as there isn t too much wear or overheating Wearing: Tearing of molecular structure; Rubber laid down on Surface; squealing of tires; creates heat
What Creates Traction? Proper Loading of Each Tire at the Appropriate Time. Stretching the Tire to reach it s Maximum Traction. Matching the Right Rubber Compound to Track Conditions. Getting the Tire Into the Correct Operating Heat Range.
Traction Circle To keep tire at Maximum Traction, You need to trade Acceleration and steer Acceleration Amount of Acceleration Maximum Traction of Tire Left Turn Amount of Steer Angle 0 0 Under Utilized Traction Braking Right Turn Tire Breaking Loose
Another Way to Think About Traction Side Bite Use more for side bite not much left for forward bite; fast corner entry Underutilized traction and side bite Forward Bite Yellow is 100% tire usage Use more for forward bite and less for side bite; slower corner entry
Tire Slip Angle The actual direction traveled will be a derivative of the two. The slip angle is the difference between the steered path and the actual path of the tire. As the tire is turned, the center of the contact patch is twisted.
Lateral Force and Slip Angle Lateral Force Produced by Tire 2500 2000 1500 1000 500 Transition Tire reaches it s stretch limit and gets into the frictional area Elastic or tire Stretch Edge of traction circle Tire stops stretching totally relies on frictional traction 2 4 6 8 10 12 Slip angle in Degrees
Longitudinal Acceleration Desired vehicle direction Contact patch area is stretched At point that contact patch releases from surface, it snaps back into position and propels car forward Contact Patch location
Longitudinal Force and Slip Ratio 1500 1250 Edge of traction circle Tractive Force 1000 750 500 250.05.10.15.20.25.30 Slip Ratio (%)
Tire is a Spring and a Shock Tire will release all of its stretch when used as a spring
Tire Grooving and Siping On tire rule tires, cutting tires into a small pattern will help build heat in tires. Small #1 blade cuts will allow the tire to feel softer and grab the asperities in the track surface. Larger grooves will allow more air to circulate around the blocks and keep them cool. Larger grooves will also dig into the track more than small grooves. Sipes will help build heat into a tire by creating friction within the blocks. Back Cutting Late Model Front Tires Keeps Them Clean and Can add Traction.
Tires Mounting and Preparation Always mount tires with serial number toward the infield Don t use excessive moisture when mounting tires Always keep tires clean between use Be sure to use enough air to push tire over safety bead and seat tire Size and organize tires before going to track If possible use nitrogen or a dry air system in tires.
Tire Grinding Grinding takes the top calloused surface off the tire. Grinding will even the surface and take the top grained surface off the tire. Grinding will take the mold release off the surface of a new tire. Atmosphere and sunlight will start to harden the surface of a tire. Grind your tires as close to the time you are going to run them as possible. Use anywhere between 60 and 120 grit sandpaper on a slow moving grinder to buff the surface. Use aluminum disks where tire rules prohibit siping.
The End Questions?