Why do my summer tires say M+S?

[Throckmorton]

I bought a set of BF Goodrich g-Force Sport Comp 2 tires in 225/50/16 for my 1996 328is. They're summer tires but they say M+S. All I could find by Googling was an article from Continental about Chinese tires being mislabeled (http://www.conti-online.com/generato..._label_en.html) and this thread about General UHP tires having the M+S stamp http://forums.evolutionm.net/evo-x-t...ted-tires.html


BTW I chose these tires because they are supposed to have a stiffer sidewall than some others, and the rubber compound is new and supposedly really good. I was looking for handling feel, not traction, since I only have 190hp so the 350 wear rating is good. I like the tread pattern too, not ricey looking like most other summer tires. Plus they're Made in the USA.

Pic of the M+S marking:



The tread:

[God Mode]

You can use them in the mud or snow.

I like those BF tires. My goto for cheap summer tires were the BF g-force sport 1. They were usable in the winter and light snow when I was too lazy to change out.

[Jimzz]

The compound is for summer so it will not work well when cold, but the tread design meets the most basic requirments for M+S. Does not mean they will work well in M+S, just meet basic Gov standards.

[phucheneh]

They're 'sort of' all seasons, as said above. Rain, slush, and other soft stuff will be shed fairly efficiently by the tire, but as also stated, the actual traction associated with the rubber is going to be poor in packed snow/ice or such.

Seems like as a general rule, most true 'all seasons' have siping. I may be wrong.

[SSSnail]

I had those exact tires on my car before I changed them out for the EC Conti DWS. The Conti, IMO, is much better, though the BFG had really good tread wear. The front tires lasted longer than 60K miles, still had some life on them when I changed them out.

[NutBucket]

I thought the solid rubber bands down the center of the tire would not allow an M+S rating? At least that's what I've noticed on every M+S tire I've looked at.

[SpatiallyAware]

M+S is simply to satisfy some requirements for passing some roads up north. Same as requiring tire chains depending on condition.

[Howard]

Originally Posted by NutBucket

I thought the solid rubber bands down the center of the tire would not allow an M+S rating? At least that's what I've noticed on every M+S tire I've looked at.

M+S doesn't mean much. A lot of tires have it even though they shouldn't.

[phucheneh]

Originally Posted by Howard

M+S doesn't mean much. A lot of tires have it even though they shouldn't.

Pretty sure there are rather complex, siped all-seasons with solid grooves down the center. Or at least close to it.

Those BFG's should shed water rather well. And like I said, I think that's about the same as 'mud and snow' as far as the rating is concerned...i.e. it will shed muddy slop or frozen slush (as in, move it from under the tire and out the sides/rear).

But snow packed down onto the road (which is basically ice)...not gonna do so well. The M+S designation is purely about the tread pattern; not the rubber compound.

[Throckmorton]

Interesting... so I guess if you have a certain amount of void space you get to put on the M+S stamp?

[jlee]

They're all-season-ish enough for the rating - check out a more serious summer tire like the Star Spec, which specifically says is not designed for use in cold temperatures.

[phucheneh]

Originally Posted by Throckmorton

Interesting... so I guess if you have a certain amount of void space you get to put on the M+S stamp?

Yup.

From HowStuffWorks (couldn't find the actual RMA doc)

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:

Extend toward the tread center at least 1/2 inch from the footprint edge, measured perpendicularly to the tread centerline.
A minimum cross-sectional width of 1/16 inch.
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.

Tires that have actually passed some kind of winter test get the 'snowflake' on the sidewall.

Basically, this is a case of fairly uncommon under-promising, really. The manufacturer advertises it as a summer/performance/whatever tire, even through it meets the somewhat worthless standards for 'all season.'

I think M+S can pretty much just be interpreted as 'it's definitely not just a track tire...but YMMV in cold weather.'