Some of the best advice we’ve ever heard: Invest in what goes between you and the ground. That means good shoes, a good mattress and good tires. People often neglect their tires or just don’t pay too much attention to them in general. It’s important to check your tires’ PSI once per month and have them rotated every 5,000 miles.
1. Skinny tires, much taller and narrower than the norm, are coming back. BMW’s i3 electric/plug-in hybrid, which relies on minimal rolling resistance to achieve acceptable driving range, is leading the charge. The i3’s Bridgestone Ecopia EP500 tires have aspect ratios ranging from 55 to 70 (narrow tread, tall outside diameter) to reduce energy loss as the tire rolls into and out of its footprint. This shape also reduces the car’s frontal area and aerodynamic drag. To compensate for a reduced air cavity and a smaller-than-normal footprint, Bridgestone uses an elevated inflation pressure to deliver the desired acceleration, braking, and cornering traction.
2. In the strictly theoretical sense, increasing just the width of a tire does nothing to improve acceleration or braking traction. A wider tire will have a shorter contact patch, which is precisely what you don’t want when the goal is maximum longitudinal grip. Jamie McNutt, the replacement-tire development manager at Bridgestone Americas, says that a longer, not wider, contact patch helps you climb faster to maximum braking grip.
3. Wider tire treads do, however, increase cornering grip. Again, though, tire engineers are always working with multiple variables. See our first point about the modern Corvette, which uses skinnier tires than its predecessor yet increases its roadholding with a stickier compound. To maximize traction in all directions, tire engineers aim for an even pressure distribution throughout the contact patch.
4. Static electricity build-up is an old concern that has returned to haunt modern tires. An inadequately grounded vehicle is an issue during refueling and when occupants slide out of the car’s interior. Modern tire compounds have become less conductive as manufacturers have greatly reduced the amount of carbon black in rubber compounds to cut weight and rolling resistance.
5. A run-flat tire can roll for more than 100 miles after it loses pressure. Tire manufacturers typically claim that a deflated run-flat can cover 50 miles at 50 mph, but if you slow down, you can stretch that distance much farther. Lee Willard, a product development engineer at Michelin, says the range roughly doubles if you drop your speed to 40 mph. Slow down more, and the range continues to grow. It’s all about reducing the amount of heat generated in the tire.
