All-season rubber stiffens and loses grip as temperatures drop toward freezing, no matter how much tread is left — that's the point where a winter-rated tire's softer compound takes over. Mount winter tires before the first hard freeze and swap back once cold weather is reliably over, rather than running them through a Baltimore summer.
The difference is the rubber compound, not just the tread pattern. All-season tires are built to stay flexible across a wide range of temperatures, but they still firm up as it gets cold, and a stiff tire grips less regardless of how deep its tread is. A winter tire's compound stays pliable well below that point, which is what actually buys back the traction, with the tread's sipes and biting edges doing the rest on snow and ice.
Baltimore's winters don't commit to one pattern — some years stay mild enough that all-seasons never get tested, others bring an ice storm that shuts roads down for a day. That's the case for going by the forecast rather than a fixed date: swap on ahead of a hard freeze, and don't wait for the first snow to do it, since the compound change happens well before snow is even in the picture.
Does every car in Baltimore actually need a dedicated winter set?
Not every driver needs them every year here, which is different from colder climates where the answer is automatic. A daily highway commute that doesn't let up when the roads turn to slush makes a stronger case than a car that mostly runs local errands on streets that get salted and plowed quickly. Worth weighing against how the car behaves now — a front-wheel-drive car with worn all-seasons in an ice storm is a very different experience from the same storm on a fresh set of winter tires.
What happens if they stay on once the weather turns warm?
The same soft compound that grips ice wears fast on warm, dry pavement, and braking distances get longer than they would on a tire built for the heat. Running winter tires year-round shortens their life for no benefit once the cold is gone, which is the case for swapping back and storing the off-season set rather than leaving either one mounted all year.
Can two winter tires go on just the front or back instead of all four?
No — that mismatches grip between the front and rear axles, which can make the car less predictable in a slide rather than more, since one end of the car grips noticeably better than the other. Winter tires go on as a full set.
Do winter tires need their own set of wheels?
Not strictly, but mounting them on a dedicated set of rims means two tire swaps a year instead of two full mount-and-balance jobs, and it saves wear on the tire bead from being remounted repeatedly.
Is tread depth the only thing that matters for winter grip?
No — the rubber compound matters just as much, if not more. A worn all-season tire with decent-looking tread can still grip worse in the cold than a winter tire with the compound built for it.