For mud and snow tires on a front-wheel-drive compact car with traction control, ABS brakes and a stick shift transmission, what is the minimum safe tread depth for driving in light snow. Let’s assume the driver is an expert at driving this vehicle in light snow.
Methinks “down to the wear-bars” is not a good answer.
3mm, if you want to adhere to the rules in Norway at least. (And we do know all about driving in winter conditions on bad roads 
)
I’m not sure there is a single, correct answer. It will depend on the tread pattern and rubber compound of the tire. Depth of tread can’t help a really poor snow tire, and probably won’t excessively hurt a good snow tire.
thank you for such a definitive answer–appreciate it
that would be 3.78/32nds in the English system for you non-metric dudes.
3mm is the legal minimum tread depth here, but the recommended minimum tread depth is 5mm (.2 inches). At 5mm they should work OK on ice and clean pavement, but even at 5mm you’ll experience decreased performance in snow.
I’ve been driving on studless winter tires made for Nordic climate for ~10 years now (and on studded tires for 20 years) and I routinely experience markedly decreased performance during the third winter (four different cars, three different brands of tires during those 10 years). The tread is a lot deeper than 5mm after those three winters.
ETA: The problem isn’t so much the tread depth as the dulling of the studs or rounding of the edges around the sipes. Those two things kill the tire’s grip
good clarification–that’s about 6.3/32nds in the English system
Nitpick—in the “English System” we don’t mix decimals and fractions. The first is about 1/8 inch and the second about 3/16 inch.
Correct, but English tire tread depth gauges are delineated in 32nds.
One would see: 4/32nds, 5/32nds, 6/32nds, 7/32nds, 8/32nds, etc.
One would not see: 1/16th, 1/8th, 1/4th, etc
Even so, they would be rounded to the nearest 32nd, not have decimal fractions.
And that is the minimum recommended? That seems awfully high to me. I would be changing tires like Indy 500 drivers.
I always used the penny trick and if you could see the top of Lincoln’s head, then time for new skins…or ~2/32nds…
true, point taken
How the heck do you drive?
I’m driving +16 kkm/year (+ ~10k miles/year), from October to April/May - that’s about half of the yearly distance - on winter tires. As I indicated upthread, I change my winter tires every three years because they’ve deteriorated to the point where I can feel the grip worsening significantly on ice, slush and snow. Studs are dulled, sipe edges are rounded and the rubber hardens. But the tread is way deeper than 5mm.
I consider it both cheaper and less awkward to spend the money for a new set of good winter tires every third year than to end up in a ditch, mashed into another car, or with a pedestrian or a moose on my hood and through my windshield because I was driving on bad tires. YMMV.
Per another post in this thread, the minimum recommeded is 3 mms or about 4/32nds
Changing the tires when the tread depth reaches 2/32nds (right at about the wear bars) is a good time to change the tires in spring/summer/fall but I’m thinking that 2/23nds is not enough tread to drive safely in light snow or worse.
my thoughts, precisely
Yep. But I only go two seasons. In any case, our winters are so long that I run snows year round. After about 30,000 miles, they are usually down to about 1/4 inch. Time for new tires.
So you drive on 4 winter tires through the winter, and then when spring comes, you put the 4 winter tires in the garage until the following winter?
I usually run the same tires year round. Perhaps I should change…
You will get much better performance in spring/summer/fall if you park your snow tires for the winter. You would notice a difference even if you switched to a “mud and snow” (M+S) tire for the non-winter months.
“Summer only” tires are also available but really spendy for only 90 days/year of usage and they are not so good in the rain.
Yup. Every friggin’ year. It’s a pain in the back, but it makes for significantly safer driving. I also throw a set of snow chains into the trunk as soon as there’s a theoretical risk of snow and don’t take them out until well into spring.
Good winter tire rubber is way too soft at summer temps (i.e. >10 deg C) and has poor traction in the summer. Just as summer tire rubber is too hard for winter temps and makes you end up in a ditch or intimately entwined with another car (or a truck!) during the winter.
For me anyways, it usually works out close enough that I just rotate my tires when I change over to the snows. So there’s not really any extra labor involved.
I’ve never changed my tires for the seasons… how common is this?