Winter Tires Stop in Half the Distance on Detroit Ice

21 feet, 2 inches. That is how far a car on winter tires slid on ice from just 10 mph before it stopped, in a test the Michigan State Police put in their winter driving toolkit. The same stop on all season tires took 39 feet, 10 inches. On summer tires it took 47 feet. We work on cars in Metro Detroit driveways all winter, and those three numbers settle most of the argument. From 10 mph, the all season car needed 18 feet, 8 inches more road.

Go Straight To

About 7 min read

What Cold Does to the Rubber

A tire grips because the rubber bends into the road. Cold makes rubber stiff. Michelin says all season rubber begins to stiffen below 45°F. A winter tire uses a softer compound that stays flexible all season, with more slits in the tread to bite into snow.

That gap shows up on snow too. Michelin says a typical car at 31 mph on snow needs 52 yards to stop on summer tires. That is 26 yards more than the same car needs on winter tires.

The best test of all season against winter tires came from next door. Quebec's transport ministry ran road tests on both in many kinds of road and weather. In a 2010 paper by ministry staff, it reports that winter tires shortened braking by an average of 25 percent. Quebec then made winter tires the law from December 15 to March 15, starting in 2008. After the first winter under that rule, the ministry counted a net drop of 5 percent in crash victims. About 90 percent of Quebec drivers already ran winter tires by 2005, so most of that gain came from the last holdouts.

Michigan has no rule like that. The choice is yours. The State Police still put it plainly in their toolkit. Switch to winter tires.

Detroit's Tire Calendar

Michelin's timing rule is simple. Switch when the average daily temperature keeps getting near 45°F, and switch back in spring once it stays above that. It also says waiting for the first snow is too late. The table puts that rule on Detroit's real weather. The temperatures and snow are the 1991 to 2020 normals from the National Weather Service.

Month	Normal high and low	Snow	Tire call
October	62.0°F, 44.0°F	0.0 in	Book the swap. Lows already sit under 45°F
November	48.6°F, 33.9°F	1.9 in	Winter tires on in the first half of the month
December	37.2°F, 25.3°F	8.9 in	Winter tires
January	32.3°F, 19.2°F	14.0 in	Winter tires
February	35.2°F, 20.8°F	12.5 in	Winter tires
March	45.9°F, 28.6°F	6.2 in	Keep them on. Nights still freeze
April	58.7°F, 39.1°F	1.5 in	Swap back once the days stay above 45°F

So the Detroit winter tire season runs about five months, from early November into April. Do not stretch it into summer. In a 2008 test, CAA Quebec found emergency stops could take up to 30 percent longer on winter tires than on all season tires in warm weather. The soft rubber that helps in January works against you in July.

Built from the Michigan State Police, Quebec ministry, Michelin and National Weather Service figures above.

Read the Sidewall Before You Buy

Two marks matter, and they do not mean the same thing.

Tire	Sidewall mark	What it means in Detroit
All season	M+S	A tread shape, not a snow test. Fine for rain and a dusting
All weather	Mountain snowflake	Passed a snow traction test and can stay on all year
Winter	Mountain snowflake	The softest cold weather rubber. Best stop on ice

Michelin says the M+S mark on an all season tire is based on tread shape and is not a certified performance test. The three peak mountain snowflake mark means the tire passed a standard traction test in severe snow. Michelin adds that the snowflake test does not cover pure ice.

That last line is why an all weather tire is a middle road, not a winter tire. The Michigan State Police say winter tires give better traction and stop more quickly than summer or all weather tires. Insurers see a difference too. Across the river in Ontario, insurers have had to offer a winter tire discount of up to 5 percent since 2016, per The Globe and Mail. The insurers one broker reviewed would not give it for all weather tires left on all year, even with the snowflake.

If you drive the Lodge and I 94 every day and park on the street, a set of real winter tires is the stronger pick. If you mostly drive when the roads are plowed and want one set, an all weather tire with the snowflake beats an M+S all season.

Studded Tires and Chains Under Michigan Law

Studs are where Detroit drivers get caught out. MCL 257.710 bars tires with metal that touches the road and studs that stick out past the tread. It makes exceptions for police in agency cars, ambulance drivers, and rural mail carriers who drive their own vehicle for the job. Reasonable tire chains are allowed when you need them for safety on snow or ice.

The same law told the state to write rules for studs, and those rules set a hard bar. Under Michigan Administrative Code R 247.174, a stud may be used only if it wears pavement at no more than 25 percent of the rate of a reference studded tire. R 247.175 then limits any device that passes to November 15 through April 1 in southern Michigan. The Upper Peninsula and the northern Lower Peninsula get October 1 through May 1.

For a Detroit driver, the safe read is no metal studs. A studless winter tire with the snowflake mark does the job and keeps you inside the law.

Make the Swap Pay Off

• Buy four. Consumer Reports says to always run four matching winter tires. Two on one end leaves the other end sliding.
• Take them off every spring. Consumer Reports says you can get three or four seasons from a set that way. Winter tires wear faster than all season tires on dry roads.
• Replace them early. Winter grip drops as the tread wears, so do not run a set down to the bars.
• Look at the lug studs. Salt rusts them, and the swap is the one time the wheels come off. A stud with heavy scale or bad threads should be replaced before the lug nut goes back on.
• Check the alignment after pothole season. A car that pulls will eat a new set of tires on one edge.
• Call your insurance agent. Ontario's rule does not reach Michigan, but one call tells you if your company offers a discount.

How We Help Before the First Snow

We do not sell tires. We do check the tire pressures on every maintenance visit, and we look underneath at no extra cost, where salt goes after lug studs and brake lines first. Our oil and maintenance and suspension and steering work runs $150 an hour, with a written quote before any part is bought, and the full price list is posted. Salt season starts the same weeks as tire season, so read our road salt car wash schedule next.