There is a lot of movement and stretching that goes on in the sidewall of a tire, and there are only so many changes that can be made. The goal is to balance sidewall stiffness with the endurance of the tire.
While a stiffer sidewall helps reduce the tire from rolling over in cornering in cars with poor camber control (the bigger problem that should be addressed), making a sidewall too stiff with more plies can give up performance in other areas such as how the footprint reacts under load, how it affects the contact patch, changes on-center reactivity, lane changes, comfort, noise, and durability. Stiffer sidewalls greatly affect the endurance of the carcass’ internals such as delaminating from deflection, stress cycles, etc.
A stiffer sidewall is not always a good thing, as it can adversely affect how the whole system of a tire works together.
When the sidewall is too stiff, it acts like a tire with too much pressure and actually loses grip.
There must be some compliance in the system to allow for some variability in the contact patch to move, react, adapt, and accommodate to dynamic situations around it. A softer sidewall allows the footprint to lay out flatter and react quicker to dynamics situations, and greatly improves longevity and “intrinsic performance” (performing well, fast lap times, made in various sizes, long lifespan, ability to perform over its life, does not oxidize, holds air, does not come unseated off the rim, easily mountable, does not tear itself apart because materials don’t like each other, resistance to road hazards, basically all the things of a tire everyone expects but does not think about).
Run Flat Tires
Manufacturers can still request Ultra High Performance (UHP) tires to be engineered as Zero Pressure (ZP) Run Flat tires. While it may be convenient to be able to drive up to 50 miles at 50mph with a flat tire, run flats add another layer of challenges to achieve the performance and ride quality targets for a UHP tire.
GM is one of the few companies that still maintain ZP Run Flats for their UHP tires. This is a choice Chevy has made for their customer to allow extended mobility in the event of a puncture.
Cup 2 Connect
Michelin recently started rolling out some sizes of Cup 2 tires with its Track Connect Technology. This new model adds a pocket built in to the inner liner of the contact patch area of the tire to hold the Track Connect sensor. Combined with app-based software, this system recommends tire pressure adjustments based off conditions and your driving as well as displaying tire temperatures and pressures. The next generation of the Michelin Pilot Sport 2 Connect, phasing in throughout 2020, will have improved traction due to compounding changes, and will have Track Connect across the entire lineup.
This is far beyond a standard Tire Pressure Monitoring System (TPMS). Track Connect is sophisticated software that recommends real-time tire pressure adjustments to maximize the performance of your tires based off how you are driving during a track session, your tire temps and pressures, your car model and tire size, and it geolocates the track and weather conditions to further optimize grip for the exact conditions.
Table of Contents:
Page 1 – Intro, My Background, Developing Bespoke Tires
Page 2 – TREAD DESIGN – Tread Depth
Page 3 – TREAD DESIGN – Circumferential Grooves, Outer Shoulder Features & Sipes, Cup 2R
Page 4 – COMPOUNDING – Compound Variation Across Tread & Tread Depth, Cup 2R
Page 5 – CONSTRUCTION – Carcass Profile/Shape, Width, Ribs
Page 6 – CONSTRUCTION – Sidewall Stiffness, Run Flat Tires, Cup 2 Connect
Page 7 – How Tread Design, Compounding, and Construction Come Together
Page 8 – Conclusion