Life is full of dilemmas. You always have to choose one thing over the other. Be it picking ice-cream over chocolate, a physique like The Hulk over the lean muscles of an MMA fighter, choice is something you cannot avoid. Same goes with a car and its components. You can opt for a bigger engine, more power and less fuel economy or go for a small engine with less power but better fuel economy. Similarly, in case of tyres, you can either have grip at the cost of ride comfort or prefer ride comfort over outright grip. Due to technological advancements, throw in fuel economy as a another factor to consider when opting for a new set of tyres. You have to choose between performance tyres that have great grip but suffer on ride quality and fuel efficiency fronts, low rolling resistance tyres that sacrifice almost everything for extracting more distance out of every litre of fuel or opt for a tyre with bigger sidewalls to have more ride comfort than anything else.
If there were not technology, what we talked about in the last few lines would always be true. However, Michelin seems to have found a solution to the problem and has come up with a tyre compound that responds in accordance with the external conditions. It is like having a tyre made of hydraulics than silica and rubber.
Before we go any further, there is a small term we need to get out of our way. This term is Hysteresis and refers to the difference between the amount of energy absorbed by the tyre due to deformation and the amount of energy released. Tyres with low hysteresis value offer low rolling resistance while those with higher value offer better grip. You can understand it better when comparing a bouncy ball and a tennis ball. When dropped from the same height, the tiny bouncy ball bounces back higher than a tennis ball, which means that the bouncy ball is absorbing a lot of energy but also releasing most of it. The tennis ball, on the other hand, doesn’t release that much energy back and instead converts it into heat. Easy enough, yes? Okay, let’s move forward.
When it’s hot, the softer compound softens further, providing even more grip which helps if you’re prepping for quarter-mile drag races. This is also why drag racers do burnouts before launching their cars/bikes. It warms up their vehicle’s tyres, ensuring they provide the best possible grip, aiding in acceleration of the vehicle.
Engineers at Michelin recently showcased a tyre compound at the Shell Eco Marathon in Michigan, Detroit, that contains silica. The presence of silica in the rubber alters the tyre’s hysteresis value when deformations occur above a certain frequency. This way, at parking lot speeds, the tyre offers low rolling resistance helping increase fuel efficiency due to less frequent deformations taking place. When the car is on the highway, tyres deform at a significantly higher rate. That’s when the tyres start absorbing energy and offer improved grip.
The engineer at the fair demonstrated the compound’s split personality by stretching the silica-loaded compound once gradually and then rapidly. When trying to rip it in two halves, it broke immediately. But when it was slowly pulled in either direction, it kept stretching like a chewing gum.
With this technology, track day lovers will appreciate the convenience of not having to change the tyres for track and road use. The same set of rubber will give you the fuel efficiency when used at sane speeds and offer high grip levels at high speeds. It also means the tyre life will be much higher if the vehicle isn’t driven at high speeds while on the highways, it will deliver grip akin to performance tyres, thereby providing the driver immense confidence.