tell me about studded snow tires

[1sttruck]

Some of the BFG AT KOs don't make the rating because of size, but otherwise they're listed as 'approved' severe rated tires by Canada. See below for some details on the rating.

http://auto.howstuffworks.com/tire3.htm

All-Season Tires with Mud and Snow Designation

If a tire has MS, M+S, M/S or M&S on it, then it meets the Rubber Manufacturers Association (RMA) guidelines for a mud and snow tire. For a tire to receive the Mud and Snow designation, it must meet these geometric requirements (taken from the bulletin "RMA Snow Tire Definitions for Passenger and Light Truck (LT) Tires"):

1. New tire treads shall have multiple pockets or slots in at least one tread edge that meet the following dimensional requirements based on mold dimensions:
a. Extend toward the tread center at least 1/2 inch from the footprint edge, measured perpendicularly to the tread centerline.
b. A minimum cross-sectional width of 1/16 inch.
c. Edges of pockets or slots at angles between 35 and 90 degrees from the direction of travel.

2. The new tire tread contact surface void area will be a minimum of 25 percent based on mold dimensions.

The rough translation of this specification is that the tire must have a row of fairly big grooves that start at the edge of the tread and extend toward the center of the tire. Also, at least 25 percent of the surface area must be grooves.

The idea is to give the tread pattern enough void space so that it can bite through the snow and get traction. However, as you can see from the specification, there is no testing involved.

To address this shortcoming, the Rubber Manufacturers Association and the tire industry have agreed on a standard that does involve testing. The designation is called Severe Snow Use and has a specific icon (see image at right), which goes next to the M/S designation.

In order to meet this standard, tires must be tested using an American Society for Testing and Materials (ASTM) testing procedure described in "RMA Definition for Passenger and Light Truck Tires for use in Severe Snow Conditions":

Tires designed for use in severe snow conditions are recognized by manufacturers to attain a traction index equal to or greater than 110 compared to the ASTM E-1136 Standard Reference Test Tire when using the ASTM F-1805 snow traction test with equivalent percentage loads.
These tires, in addition to meeting the geometrical requirements for an M/S designation, are tested on snow using a standardized test procedure.They have to do better than the standard reference tire in order to meet the requirements for Severe Snow Use.

 

[rpn453]

Thanks for the info, 1sttruck. I didn't know what defined a M&S tire before reading that.

I believe the only BFG AT that doesn't meet the severe snow standard is the 35" (315/70R17) size. There probably are better dedicated snow tires than the AT's, but I'd take them over almost any all-season tire for winter.

 

[lobo11]

So are you saying all but their very wide tires meet the M&S designation? I can believe that, however, after driving a true severe weather rated tire and having owned BFG TA KO tires I just do not believe they would ever meet the "severe weather" rating with the snowflake & mountain symbol. They are nice tires, and I have no doubts about being M&S rated, but not severe weather. If these tires tested and passed the severe weather ratings it would be shouted from the roof tops and stamped on the side wall for all to see that BFG makes a LT tire with a 60K mile warranty that meets severe weather service. I will say again the difference between a M&S rated tire, and severe weather rated is very significant.

 

[1sttruck]

"....BFG makes a LT tire with a 60K mile warranty that meets severe weather service."

Yes, along with the Goodyear Silent Armor Wrangler they're some of the very few (only ?)regular AT tires that are severe snow rated. I wasn't aware of the warranty though - does it apply to 3/4 and 1 ton trucks ?

 

[1sttruck]

Looking at the BFG site the BFG AT KO is now offered in load range E in some sizes, but the treadwear warranty appears to be offered for other tires.

 

[Gary Allan]

Love studded tires. I don't have them for my jeeps ..but I did for my mother's FWD cars. 4 studded snows on dedicated rims. They lasted about 6 seasons, IIRC.

 

[Thorn]

I can't say enough good things about the four studded Nokian Hakka 1's that I use on my AWD Subaru. I commute about 100 miles per day from northeast Pa into central PA, and the highway is jam-packed with eighteen wheelers (they don't call it the Keystone state for nothing), oftentimes flying by at what I consider unsafe speeds for the road conditions.

I have run these Nokians for four winters now (this will be my fifth upcoming) and the treadwear and durability of the studs has been tremendous. As soon as these tires have seen their day, I will run right out and try to replace them with the exact same set-up.

My daily commute can be a white-knuckle experience when the weather turns bad, mostly because of the heavy truck traffic. These tires work great in snow/slush, and the studs provide an added measure of safety for those times when we get freezing rain and/or "black ice" left over after the plow trucks have cleaned the majority of the snow away.