Whoever
coined the term "all-season tyre" in
the late 1970s probably wasn't trying to mislead tyre buyers.
Instead, they were trying to play catch-up with Goodyear's hugely
successful Tiempo, a tyre that was wonderful "for all seasons,
for all year," according
to its TV jingle.
Still, near-universal confusion sprung from the name all-season. Most people have the mistaken belief that all-season tyres are better in spring showers and fall rains than regular tyres. (Regular tyres have become known as summer or, more accurately, three-season tyres.) I've found many tyre-company employees, automaker engineers, and car writers who don't know the correct answer, either.
Here's the truth: "All-season" doesn't mean the tyre has great performance in all seasons. It means that the tyre is a compromise—the designer traded wet grip to gain some mobility in snow, give drivers tyres that could provide adequate year-round performance, and save them the trouble of changing their tyres before and after the winter.
But "some mobility in snow" is not the same thing as "good grip in snow." The snow traction of all-season tyres varies from great to almost none. And an all-season tyre has less damp-road grip than an otherwise equal summer tyre from the same manufacturer. So winter is the only season when an all-season tyre offers more traction than a summer tyre. If you live where it never snows, the three-season regular tyre always holds the traction advantage.
Still, near-universal confusion sprung from the name all-season. Most people have the mistaken belief that all-season tyres are better in spring showers and fall rains than regular tyres. (Regular tyres have become known as summer or, more accurately, three-season tyres.) I've found many tyre-company employees, automaker engineers, and car writers who don't know the correct answer, either.
Here's the truth: "All-season" doesn't mean the tyre has great performance in all seasons. It means that the tyre is a compromise—the designer traded wet grip to gain some mobility in snow, give drivers tyres that could provide adequate year-round performance, and save them the trouble of changing their tyres before and after the winter.
But "some mobility in snow" is not the same thing as "good grip in snow." The snow traction of all-season tyres varies from great to almost none. And an all-season tyre has less damp-road grip than an otherwise equal summer tyre from the same manufacturer. So winter is the only season when an all-season tyre offers more traction than a summer tyre. If you live where it never snows, the three-season regular tyre always holds the traction advantage.
Rain and Snow
Another bit that adds to the confusion: A tyre's ability to disperse deep water is independent of its all- or three-season designation. Stay with me: On damp or lightly wet roads, it's your tread rubber, often called the compound, that's the main factor in determining traction. Stickier and softer compound is better for both dry and damp pavement.
But in deep water and at high speeds, a tyre's ability to stay in contact with the pavement (tyre engineers call it hydroplaning resistance) depends more on the tread pattern: the lateral and longitudinal grooves. Tread patterns that are excellent at dispersing water can be found on both all-season and summer tyres. Not-so-good tread patterns are found on both too. Lastly, wear matters a lot. If underinflated or half-worn, a tyre with a wonderful compound and a great tread pattern may not match a mediocre tyre that's brand-new and inflated to the vehicle manufacturer's specifications.
Summer (or regular or three-season) tyres have inadequate snow traction for the same reason they provide great damp-road traction: their soft, grippy tread compound. That compound starts to harden at subfreezing temperatures. An all-season tyre trades the summer tyre's damp-road grip for the ability to remain flexible at well-below-zero temperatures.
What to Buy
If you're seeking replacement tyres that will increase traction on wet and damp roads, switch from your original-equipment all-season tyres to summer tyres. The opposite is true, too. If your performance car, all-wheel drive or not, is terrible in the snow, the fault can almost certainly traced to its summer tyres.
When looking for summer tyres to replace not-so-grippy all-season tyres, see if the maker of your original tyres offers a summer tyre with the same model name, but without the A/S (all-season) suffix. That's your best bet. If your car came with summer tyres and you fear getting caught in a snow shower, you're in luck if the maker of your original equipment tyres produces an all-season version of that model.
If those choices aren't available, check for new options at online tyre stores. There is no tyre industry standard or government specification for all-season, summer, or three-season tyres. tyre companies make their own assessments, and those assessments are far from uniform among manufacturers. So read the reviews online. Ignore the outliers and look for a general agreement.
While it may or may not be true that clothes make the person, the right tyres can make a mediocre car excel, and the wrong tyres can turn a beauty into a beast.
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