Summer vs all-season tires: what you gain and give up

Three things separate a summer tire from an all-season. The rubber compound is tuned for warm temperatures. The tread has fewer grooves and fewer sipes (the small slits that help with snow), which puts more rubber on the road; Bridgestone notes that summer tires may also have shallower tread for stability near the limit. And the sidewall carries no M+S (mud and snow) marking. Michelin says tires without M+S aren’t recommended for winter driving where winters occur.

Automakers are blunter about it. GM’s service bulletins call summer tires “3 season performance tires”. Labels such as “max performance”, “ultra-high performance” and “high performance” have no standard definition, and makers use them inconsistently, so compare specs rather than category names.

Summer rubber stiffens as it gets cold, and stiff rubber grips less. That happens on dry pavement too: Michelin says summer tires lose grip below 45°F even on cold, dry roads. Here is where tire makers and automakers draw the line:

Honda’s tire information for the Civic Type R goes as far as warning that using summer tires below 45°F may lead to loss of control. Nobody suggests the tires stop working at exactly 45°F, but if your mornings regularly fall below it, a summer tire is working outside its design range.

Cold weather is more than a grip problem for summer tires. GM and Ford both warn that below about 20°F (−7°C), the rubber loses so much flexibility that it can crack in the tread and shoulders. GM says to avoid driving or even moving a car on high-performance summer tires below that temperature, and that the cracks, while they don’t leak air, do damage the tire. Its advice is to discard tires that show tread cracks after cold-weather use.

Honda gives a different figure, saying the tread may become brittle below −4°F (−20°C), but the 20°F figure is the one most automakers document. If your car lives outside in a cold climate, that is a strong reason to swap to a winter set before the first deep freeze.

Tire makers are candid about the compromise. Bridgestone says all-season tires may give less grip than summer tires, with some loss in steering, braking and cornering, in exchange for light-winter capability and longer tread life. Rain isn’t the summer tire’s weakness: Bridgestone notes summer tires perform well in the wet, because their tread is designed to clear water.

The longer life shows up in the numbers. Here is what three makers publish for a summer tire and its all-season sibling:

The UTQG grades on a sidewall are useful for comparing summer and all-season tires, but each one measures something narrow. The federal rule that defines them is specific:

So a summer tire and an all-season tire can both be graded AA for traction and still behave very differently on a cold morning or in a fast corner. For the full breakdown, see UTQG ratings explained.

Replacing factory summer tires with all-seasons is common and usually fine, with conditions. Michelin says a replacement’s speed rating should equal or exceed the original; a lower rating limits the car’s top speed and can change handling. Honda says to match size, load range, speed rating and maximum pressure. Summer tires are mostly rated W, Y or (Y), and the all-season siblings above reach Y in many sizes but include more W and V sizes, so check yours. Bridgestone recommends all four tires be the same type. Some automakers approve specific tires: Porsche says only its N-marked tires are tested and approved for its cars.

If your winters bring regular cold, snow or ice, the alternative is two sets. Michelin suggests switching to winter tires when average daily temperatures fall below 45°F and switching back once they stay above it, and calls two sets the safer approach where winters are real. A middle option is an all-weather tire with the three-peak mountain snowflake, which stays on all year; our guide to 3PMSF vs M+S explains what that symbol certifies.