Back in October, the Museum of Science in Boston unveiled a new installation – a tire. The BluEarth-1, an ecologically-friendly prototype tire made by Yokohama was placed in the Transportation, Nanotechnology and Renewable Energy exhibit hall, due to it's strong associations with all three. The BluEarth-1 was made with a resin derived from orange oil, which is not only a renewable resource, but has a remarkably positive effect on the rubber composition of the tire on a molecular scale. Although there have been limited lines of orange oil-based tires available in Europe,Yokohama's new Avid Ascend Grand Touring tire is the first consumer tire to reach the US that uses this technology, and really the first tire to bring the technology entirely to fruition.
- Smooth as silk when going straight.
- Sticky as spider silk when turning.
Orange Oil Compound Yokohama uses a resin derived from orange oil – acquired from orange peels after the oranges are used for juice – to replace some of the petroleum-based oils used in making tires. The exact amount that is used per tires is unknown, but Yokahama engineers say that the orange oil in the compound “helps create a tighter bond between natural and synthetic rubber at the molecular level.” This has some very interesting effects within the compound.
Normally, rubber compounds that are grippier will not only have greater rolling resistance due to their grip, but will wear much faster than harder compounds with less grip. Yokohama claims that their orange oil compound is thermo-reactive at a molecular level, meaning that at normal operating temperatures for straight-line driving the rubber is harder, lower resistance and wears longer. However, when the tire takes a corner or is otherwise subjected to lateral pressures, the rubber heats up. As the rubber soaks up heat it becomes softer and grippier. This has some rather obvious advantages.
Adaptive Siping Yokohama uses three-dimensional locking sipes, which prevent the tread blocks from flexing too much. This increases wear resistance and lowers rolling resistance from tread flex. In a very interesting attempt to offset the grip that is lost to treadwear, Yokohama's sipes also change pattern as they wear down, becoming more aggressive as the tread itself becomes shallower.
Yokohama's admittedly brilliant idea to give journalists as much seat time on their tires as possible was to fit the tires on to a number of different rental cars, including a Ford Focus, a Cadillac SRT and a Prius, for the two-hour trip from Orlando to Sebring Raceway. Consequently, by the end of the day, we had each put in four hours of driving time on the Avid Ascends, plenty of time to get an excellent idea of the real-world performance of these tires.
Driving in a straight line at any speed, these tires are easily as silky-smooth as any I've ever driven. Driving the tires on smooth highway was very much like driving on glass. They are also extremely quiet. At one point I pulled up alongside another journalist on the highway just to listen to the tires' almost inaudible hiss. At times it seems as if they can have no grip whatsoever. Crank the car into a hard turn, however, ask for grip and the magic happens.
I'm very familiar with the concept of “progressive grip.” Some tires lose grip all at once, with no warning. Others have a more progressive grip, a longer threshold of “chirp time” before they will break loose altogether, providing the driver with much more warning and control of a low-grip situation.This is the first tire I've ever driven to progressively gain grip. The harder I turn the car, the stickier the tires feel. Of course, traveling on public (and patrolled) highways and roads, I was not going to able to find a chance to find a break-loose point, but taking hard 90-degree turns somewhat too fast at intersections failed to even chirp the tires.
A number of overly-quick lane changes and some surreptitious avoidance maneuvers on deserted roads did reveal a slight weakness to the tires – they seem to have a built-in quarter- to half-second delay before the grip really dials in. I suspect that it takes that long for heat buildup to activate the compound. I'm also unsure of how fast the heat buildup will dissipate and what effect that will have on the tire in the long term, although the tires certainly do carry a UTQG temperature rating of either A or B, depending on the size
The Bottom Line:
For all their appeal to tire geeks like myself, the Avid Ascend delivers what it promises, smooth ride, excellent grip and low rolling resistance. Whether or not using orange oil is really resulting in the replacement of large amounts of petroleum-based oils or whether, as I suspect, the amount of orange oil in the tires is actually rather small, the effect of the orange oil is quite noticeable. Yokohama's actual commitment to ecological construction methods is not in question – the tires are constructed at a zero-waste, zero-emissions plant in Virginia.
Yokohama is to be complimented not only for making one heck of a Grand Touring tire, but also for pushing the technological envelope forward for all tires in a major way. We are at the very beginning of a technological revolution in several different aspects of tire design construction. Siping patterns, rubber compounds and construction methods are all undergoing a quantum evolution right now, and Yokohama is right at the forefront of all of these movements. Where all this is going is yet to be seen, but Yokohama's approach shows a lot of promise.