Snow Tires & Tread Depth

While preparing for the winter months I have received two different opinions on when to replace my winter tires based on tread depth. Currently the numbers are 9-6-7-4. One side states that no tire ever needs to be replaced until nearing the 2/32nds depth while the other side (supported by articles on TireRack and Consumer Reports) states that for winter tires I should be thinking about replacing anything from 6-7/32nds and below.

Is there a different standard when it comes to winter tires in order to preserve the traction capabilities for the snow/ice?

Thank you for any assistance that you can offer!

@CapriRacer

Could you shed some light on this? I wouldn’t know the answer even if I consulted the Magic 8 Ball.

Just from the uneven tire tread depth, I think your winter tires should be replaced and determine why the uneven wear. Are your summer tires also showing the odd wear pattern?
I would think 2/32 would be worthless in snow.

2 Likes

The tread depths were taken at the end of last season (March '21) after an alignment at the dealer (November '20). The summer set of tires are all wearing at the same rate as were the winter tires until that last reading.

The 9/32nds tread is from a replacement tire due to a road hazard (November '20); the 6&7/32nds treads are from three years of winter driving; and the 4/32nds tread from the right rear after the last rotation is the confusing one.

Rotations done between 6,000 and 7,000 miles (usually).

As for treads of 2/32nds: Both the local tire shop and the tire manufacturer’s customer support line stated this value as the legal limit but added that I should replace the tires sooner if I felt unsafe on the road. Neither party indicated a different standard for snow tires based on “needed” traction/control.

I apologize for miscounting the seasons. It actually has been only two years of winter driving not three.

I would replace the snow tires at 5-6/32 tread wear if you want good traction in the snow and ice.They will become good all season tires if you decide to drive on them for the summer but they will be noisy.

My blizzaks were 1/2 tread, maybe 8/32 and had winter rims. I got new average quality all season tires in nov and I put blizzaks on in December and the blizzaks were worse then my new a/s tires.
2 sets of tires let’s you extend tires life and choose when to install them. I wanted new tires before snow, not in spring. Selling winter tires is easy in mn

They’re right. 2/32 is worthless as a snow/winter tire.

1 Like

6/32 seems like a pretty good cutoff point for snow tires. I used to live in high altitude Colorado snow country, but don’t ever recall measuring the treads. I just replaced the snow tires when they looked like they needed it, or if they weren’t providing enough traction. If the area you are located allows tires w/inserted tread spikes, those work considerably better than just rubber treads. I didn’t need to use the spikes with my front wheel drive sedan, but I did use them on my rear wheel drive truck.

Only on ice, on bare or wet roads studded tires are worse.

I don’t drive in snow with less than 6/32 tread.

That tire was on the right front before the tires were rotated, the right front has the most wear. Replace the 4/32" tire, the others have sufficient tread.

Blizzaks have it worse than some other winter tires. Their special compound for winter driving does not extend beyond the top 55% of the tread. This means that half worn Blizzaks begin to perform like all season tires just when you really need them to work. This is part of why I stick with Michelin X-Ice or General Altimax Arctic tires in the winter and I never run them below 5/32 because nobody ever feels the smugness of saving a few bucks on tires as they slide off the road into a ditch (or worse).

1 Like

The Physics: Wet traction and snow traction vary according to tread depth remaining (TDR). The curve is smooth, without breaks or inflection points. That means there is no obvious point below which one could declare that there isn’t enough TDR. Please note that even smooth tires (slicks, bald) have some wet and snow traction.

The Law: The US Federal government has a requirement that all tires have a “Tread Wear Indicator” (TWI) that appears when the tire is worn to 2/32nds of a inch TDR. This is commonly called “the Legal Minimum”, but there is no US law or regulation that says that the tire can not be used - because this is supposed to be the individual states’ jurisdiction.

The US states are all over the map (get it?) when it comes to legal minimum TDR’s. Some say nothing, some say 2/32nds, some say 4/32nds for commercial vehicles, etc. I’m sure someone somewhere has compiled a list.

Other countries are also all over the map (Boy, I sure like that joke!). Some use 2/32nds (1.6mm), some use 3 mm, some don’t have any regulation, some don’t even require the 2/32nds TWI, but most either line up with the US regulation on TWI or are tolerant of it.

The tire industry seems to have coalesced around 4/32nds as the point to remove tires from service for wet traction reasons, and, to a lesser extent, 5/32nds for winter tires for snow traction reasons.

1 Like

Thank you for all of your insights! Here in Michigan studded tires were outlawed in the mid-1970s and the legal limits on tread depth remaining for vehicles under 10,000 pounds is 2/32nds front and back [Michigan Vehicle Code (Act 300 of 1949), 257.710.h.iii].