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Patrick Bedard

Extremists are on a roll these days, usually in packs of four. In fact, a four-pack is waiting for me out on the driveway. Our long-term Lexus IS300 wears four Goodyear Eagle GS-D 215/ 45ZR-17s. The 45 in that string of characters is the aspect ratio; the tires' crosssection height divided by section width comes out to 0.45. Any tire that's less than half as tall as it is wide, less than 50 when you lose the decimal point, is an extremist in my book.

They look extreme. "Hey, Bud, check the tires on that fork lift!" And they work extreme. I got stuck last week, four blocks from home.

Extreme "performance" tires turn antiperformance in winter weather, in part because the soft tread compound goes very hard as temper~tures drop near freezing; the wonderful ability to conform, llmost flow, into road texture ~oes away. And so does the grip. ['hat flame-blue Lexus has been liding from snow since ~ovember. Finally, it fell, six lches over night, heavy and wet t 34 degrees.

With the console button witched to "Snow," and the tracon control moaning and grunting, e crept around the comer, up the se, across the flat, then left on to a ight upgrade. That's when the ars gave up and started to spin, and avity did its thing, pulled them jeways down the road's crown, ward the ditch-SOP for a reariver. I walked home for a shovel.

The wide tires had compressed the wet snow to a dense layer about the thickness of cake frosting, and they had rolled up on top, unable to grab pavement. This is the nature of remist tires; as the aspect ratio drops, the contact patch gets shorter and wider, like a flotation tire. A different tread pattern can tune behavior for different conditions, but tweak all you want, extremist tires will never be happy in the snow.

Lexus is upfront about this, calling the 45s "summer" tires. A set of 205/55s on smaller, 16-inch rinls is a no-cost option for all-weather driving. Only nine percent of IS300 buyers choose the sensible shoes.

I'm not Surprised. They're buying a sexy car. Who wouldn't want the sexy tires? Indeed, who would say no to "performance"?

On this staff of passionate enthusiasts, dare I say "me"?

Oh, if the car were to live its entire life in Southern California, or Florida, I'd maybe go with the extremists. Or if it were truly an extremist car, a Ferrari 360 Modena, say, then sure, they were made for each other. But for an all-purpose car such as the IS300, I want all-purpose tires.

That means M+S appears somewhere on the sidewall, the official indicator mark of "all-season" tires. But from here we get into deep vagueness. M+S is little more than an agreement among tiremakers that the footprint will be 25-percent empty space. This suggests lots of little grooves to drain away standing water, and sharp edges to dig dow·n through snow. But there's no traction test. So M+S doesn't actually guarantee a minimal amount of grip on a slippery day.

You have even less to go on when seeking "performance": There's no mark for it. A Z rating indicates only durability at speeds above 149 mph (Wand Y lift the rating up to 168 and 186, respectively). A Z rating and no M+S mark, together, usually indicate a "performance" tire.

I'm not suggesting there's no joy in extremist tires. You'll get an extra 0.01 or 0.02 g on the skidpad, if. And a bit shorter stops, as many as maybe 10 fewer feet from 70 mph, if. They're dam good in the (warm) rain, if. They also bring right-now responses to the steering, with WYSIWYG path control (What You Steer Is What You Get) at most cornering speeds short of reckless. That is, if.

But these are big ifs.lfthe suspension and the anti-lock brakes and the steering are factory-calibrated for extremists, you'll get those benefits, although the rain performance goes away fast as the tread wears. If, on the other hand, you fit extremists to a car t wasn't intended for them, there's a gc chance that some of these joys will turn groans. Straight-ahead steering often tw truculent, Particularly on lanes worn heavy trucks.

Even if your car likes them, the liab ities are considerable. The ride will I harsher. Tread life will be shorter, becau the tread compound is softer. If you live snow country, you will need a set of wint tires. On all these points, experts will argt about the size of the trade-offs-in fact,they vary with every brand and model ( tire-but there's no disputing the directio of them.

Experts argue, too, about the subjectiv details of handling, and here's where I side with a small minority on this staff. Fun tires, fa me, slip noticeably, slip readily.

All tires develop , "slip angle" during cor. nering. As a practical definition, consider it to be the difference between the direction toward which the tire is steered and its actual path. Sensing slip angles, and controlling them, is the basic technique of performance driving. And once you're thinking about them, they're easily discerned. One example: A car's drift angle is, in fact, the slip angle of the rear tires (if you discount the small steer angle imparted to the rears by the suspension geometry as the body rolls).

Extremist tires, with their low, stiff sidewalls, comer with narrow slip angles, so small you're barely aware of them. That's what gives the WYSIWYG steering, and extrernists maintain WYSIWYG up to very high cornering forces; the car feels as if it were on rails. But it's on tires, and all tires slip big time if you push them too far.

The problem with extremists: By the time you feel the slip, you're going seriously fast, with very little time to react. For street driving, I prefer tires that develop discernible slip angles at modest side forces. I want to feel that angle get wider as the g rises, and more important, get wider at a quickening rate. This rate of widening is the clue to anticipating the limits.

I also think feeling drift angles is more fun than being on rails.

The M+S designation is a frustratingly vague promise. It describes a broad range of tires from "almost performance" to "almost snow." But compared with extremists, M+S tires generally have a taller sideWall, and narrower tread blocks that lean over more as the forces build. These design details increase the flexibility of the tire and increase slip angle. They also increase wearing days to 365 a year.

If I have to go out in the snow, then so do my tires.