Tires that give up their lives for driving pleasure

by Patrick Bedard
Submitted by Michael Sands
HTMLized by David Hwang
Presented on the NSX Home Page February 19, 1995

Nobody expects anything about a Ferrari to be ordinary, and if a Ferrari, left to itself for just a moment, were to snarl and gobble up some Shih Tzu that wandered too close, people would say, "Yeah, jeez, those Ferraris, they're sumthin."

If some Ferrari owner mentioned that he'd worn his rear tires bald as honeydews in 3000 miles, people'd shake their heads and say, "Yeah, jeez, those Ferraris, they're too much."

And if the guy sued Ferrari because his car ate its tires down to the rinds while he was enjoying the g's, people would laugh and say, "Hey, Butt-head, you knew it was a Ferrari when you bought it."

Among adults, it's just understood that a thigh-high two-seater with the immoderate looks of a Ferrari, and the immoderate performance, is probably going to have some pretty immoderate appetites when it comes to gas, tires, spark plugs, and insurance premiums too. Immoderation is a Ferrari's reason for being, and if owners sue the maker over immoderate tire wear, I've never heard about it.

There are, however, several suits against Honda over tire wear on the Acura NSX, one of them alleging that the rears lasted only 3000 miles. Whoee, what a joy ride that must have been--about the most fun a guy could have sitting down, I reckon. This has the smell of a money grab. Honda is definitely a deep pocket, and I'm getting a whiff of shysters tossing out the bait to other owners, hoping they'll pile on for a class action.

If someone truly feels wronged here, he's operating on the delusion that a thigh-high two-seater with the immoderate looks and performance of a Ferrari must, if it's from Honda, be as ordinary as a hatchback Civic. Poor man, because that means he doesn't appreciate what a technowonderful steed he's driving.

It's easy to underestimate the NSX; its discount price (compared with Ferrari) and its charm-school manners can both be mistaken for admissions that there's nothing special going on down under the paint. But I've never seen another production car in which the technical trade-offs were so carefully weighed, then resolved in favor of the far-out solution. If Honda has bean counters, by the time the NSX development bills were paid, they, too, must have been bald as honeydews.

Weight, of course, is the enemy of immoderate g's. So Honda went to the enormous cost and risk of building the unit body and suspension structure out of aluminum. Show me another all-aluminum sports car.

Bulk is the enemy of performance too. So the NSX has a small engine wrapped in a small frontal area. To make the 3.0-liter V-6 perform, in effect, bigger than it is, Honda pushed the operating range up to 8000 rpm. VTEC, a variable valve-timing arrangement, enables it to breathe at the high end (without sacrificing the midrange) while high-cost titanium connecting rods pare stresses so it can live up there too. This clever recipe for power without bulk has another payoff--power without big torque, so the drivetrain can also be light.

Are you beginning to suspect that such venturesome engineers might also try for a bit extra from the tires? Consider the opportunity. Tires are the final link in the guidance system. And their postcard-size footprints are the only contact with the road. Engineers motivated enough to do an aluminum body, VTEC valvetrain, and titanium rods are hardly the sort to quit when they finish the wheel rims. In fact, NSX tires are so venturesome that each corner of the car wears a different part number.

This is not entirely unheard of on high-performance sports cars. If the fronts are a different size than the rears, that's two part numbers. Then if the tread is directional and asymmetric, that's two more.

The best rain tire is one with lots of open space in the tread. But the best dry tire has no open space whatsoever. Directional tread makes grooves more efficient so they can be smaller. The idea here is to shape the lateral grooves so they touch the pavement first at the tire's middle. Then, as the tire rotates, the section of the groove squeezed against the pavement moves outward, pumping water outward too. Adding asymmetric to directional is the final reach for the best of both worlds. In cornering, the tread blocks at the outer edge of the tire do the most work. So they'd like to be large. But large is bad for rain. Asymmetric tread, then, gains dry grip with large blocks at the outside, and makes up for it in the wet with more open spaces on the lightly loaded inside.

A carmaker has to want performance a lot to specify directional and asymmetric tread patterns, because the costs leap--the tire maker needs both left and right molds, and the supply system has to accommodate twice as many combinations. Honda, however, wanted even more for the NSX. Its tires have asymmetric construction too; the carcass going into the mold is different for each corner of the car. There's a built-in ply steer. Instead of rolling straight down the road, each front tries to steer away from the center of the car, and each rear steers toward the center. These steers cancel each other out across the car, so the path remains straight. But the canceling has the effect of pre-tensioning all the tires and the suspension, rather like clenching muscles in anticipation of motion. So when the driver makes a steering input, there's no slack to take up--the whole car is tensed to move.

On the road, the NSX is magic. It steers so quickly and progressively to the touch. Even better, there's no indecision, and no wiggle at the rear when you hustle into a curve. You have no sense of waiting for the slip angles to build back there as you do in other cars. Not having to wait to see what develops, if you think about it, is the perfect preemptive strike against all predictability problems. You needn't predict, because you already know.

This predictability as you press the limits, in fact, is what makes the NSX such a great street car. And in my years of racing, I never drove a competition car with as much finesse. Ironically, such predictability is not so necessary on the track, because the driver operates in such a highly practiced state; he's done the same turn just seconds before. But a street driver takes every turn cold; a familiar turn means yesterday, or last week. And he gets little, if any, practice at the car's limits. So predictability is everything, and if it were easy to make a sports car as predictable as the NSX, somebody else would have done it already.

Of course, no one is suing because the NSX handles too securely. The complaint is tire life, which comes down to cost. What's a fair price for the NSX's immoderate finesse?

Certainly Honda paid a price. Other tires--notably the Goodyear Eagle GS-Cs on the Corvette, Camaro Z28, and a few more cars--have treads that are both directional and asymmetric. But the carcass that goes into the right and left molds is the same, and Goodyear spokesman Dave Wilkins said he couldn't think of any other tires, apart from those of the NSX, that weren't made that way.

Honda has gone out of its way, too, to say the NSX has special tires. When the car was introduced to the U.S. automotive press in spring 1990, a Yokohama engineer was given time to explain how his company worked side by side with Honda to create what he called "dream of a lifetime" tires matched exactly to this car.

"The ply steer is one of the major [handling] enhancements," says Tom Griffing, Yokohama's national technical service manager. "It also has the ability to wear the tread quicker than normal." Of course. It's constantly scuffing the tread, much like toe-in or toe-out.

Griffing is responsible for customer relations, so he hears the complaints, and he's heard them about baldies in 3000 miles. "Average life of the rears is ten to twelve thousand miles," he says. The fronts go about twice that.

Perhaps to warm up the customers to the idea of replacing tires, there's a glovebox booklet supplied by Yokohama; The High-Performance Tires on Your High-Performance Sports Car. It has gone into every NSX since partway through the first model year, according to Honda's Mike Spencer. Four of the six chapters listed on the table of contents talk about tire wear.

You're waiting for the thud, right? How bad is the bill for these "dream" tires? I called The Tire Rack, a ship-directly-to-you seller of most brands. When I asked for exact-replacement tires for the NSX, Ed Gosey told me, "Oh, yes, we sell a lot of those." For Yokohama AO22H1s as used through the 1993 model year, fronts are $149, rears are $186. How does that compare with tires for other sports cars of immoderate performance? Gosey quotes Goodyear Eagle GS-C replacements for a 1993 Corvette ZR-1 at $243 front, $309 rear. Corvette owners pay 65-percent more; they get maybe twice the tread life and half the handling finesse.

Right here would be a good time to laugh and say to these litigating NSX owners: "Hey, Butt-heads, you don't know how good you've got it."