What Does M+S Mean on a Tire?

Buying new tires today seems more confusing than ever before. Not only do you have to choose the correct size, speed, and load rating, but you also need to be sure that the type of tire fits the weather in your area. Make the wrong choice, and you might be having real issues in harsh wintry conditions, like snow and ice.

For those reasons, tiremakers put all sorts of symbols on the side of the tire. These should be helpful, but from what I learned in the past two decades, people are even more confused by those markings. That is especially true for the M+S letters, which most people associate with a tire that will be perfectly fine to drive on snow-covered roads.

However, that is far from the truth. In fact, M+S tires are so varied today and so different from each other that the symbol has largely lost its significance. But what does M+S really mean, and how does it convert into on-road and off-road performance?

In this article, I will crack the code and navigate the labyrinth of tire markings to give you a clear picture of what M+S classification means and also compare it to the modern Three-Peak Mountain Snowflake (3PMSF) alternative. So, without further ado, let's decipher the M+S terminology!

Decoding Tire Markings

The sidewall of your tire hosts an array of symbols, letters, and numbers, a complex matrix that is anything but arbitrary. Although most of them go unnoticed by the driver, each one contains important information for the size, speed rating, load capacity, performance capabilities, and the conditions they are designed to tackle.

Even some seasoned car enthusiasts would have issues understanding everything that is written on the sidewall of the tires, which is why I will start this article with an extensive rundown of all markings. Understanding these markings can give you the knowledge needed to choose the right tire for your specific requirements and provide insights into maintaining optimal tire performance.

1. Understanding the Alphabet Soup of Tire Markings

A typical tire marking might read something like "P205/55R16 91H M+S." Let's break it down:

• "P" indicates that the tire is a Passenger type designed for passenger vehicles. However, this letter is usually omitted from most tires, and you can mainly see it on crossover/SUV tires, where LT (Light Truck) sizes are also available.
• "205" represents the tire's width in millimeters from sidewall to sidewall.
• "55" is the aspect ratio, the height of the tire sidewall expressed as a percentage of its width.
• "R" denotes the construction type – Radial, which means the tire layers run radially across the tire. Another construction type would be bias-ply, but such tires are mainly used in special-purpose vehicles today.
• "16" refers to the wheel diameter in inches, the size of the wheel the tire is designed to fit.
• "91" is the load index, a numerical code that correlates with the maximum load the tire can carry.
• "H" is the speed rating, indicating the maximum speed the tire can maintain under its rated load capacity.

But what about the M+S symbol often found at the end of this string of characters?

2. What Does M+S Mean on a Tire?

The M+S symbol means Mud and Snow. As such, a tire with this symbol has a tread pattern that is designed to improve performance in muddy and snowy conditions. In other words, the tread pattern on these tires would have more prominent grooves than summer tires, enabling the tires to compact snow and mud within these voids and then release them as the tire continues to roll. Moreover, M+S tires have some sipes that would give additional biting edges.

The symbol is widely used for all-season and winter tires today. Tire manufacturers use it to show the capabilities of the tire, i.e., that it can be used in all weather conditions. However, the M+S symbol is not a subject of any performance criteria, meaning some tiremakers could even put it on their summer tires if they wanted to.

Consequently, M+S tires can vary widely in their actual performance capabilities, depending on factors such as the tread compound, the specific design of the tread blocks, and other technological features incorporated into the tire by the manufacturer. In other words, you should absolutely not trust the M+S symbol and instead look for expert reviews on every tire.

Lately, there is a more specific marking that focuses on higher longitudinal traction on snow – the Three-Peak Mountain Snowflake (3PMSF) symbol. The marking looks like a mountain with three peaks and a snowflake over it and is subject to independent testing. But, more on the 3PMSF rating later.

The History of the M+S Symbol

The M+S or M/S designation, standing for Mud and Snow, has its origins in the early days of the automobile industry when driving conditions were often challenging, and tire technology was in its nascent stages. In those days, the tires needed to be good at tackling off-road paths simply because there were not so many paved roads.

The M+S symbol was introduced by tire manufacturers in the mid-twentieth century as an answer to this demand for tires that could perform well in less-than-ideal conditions, specifically those involving mud and snow. However, it was more of a commitment by the tire industry, not an independently testable symbol.

The first tires to bear the symbol were truck tires because, obviously, these vehicles covered the most miles and the worst roads. However, the M+S symbol expanded over time and started being used in passenger vehicles, providing the foundation for the development of winter and, later, all-season tires.

Unraveling the M+S Classification

Now that you know what the M+S symbol means, let's have a closer look at what it really brings to the table.

1. The M in M+S

The M means mud, meaning the tire has a specific tread pattern that can tackle mud. But, in all reality, do you really think most M+S tires are able to tackle mud? Sure, they might be fine on some very shallow mud, but for anything more serious, you will need an all-terrain or an off-road tire.

These tires have broader and deeper grooves, also known as voids, that allow for better traction in mud by allowing the mud to enter and be ejected from these voids as the tire rolls.

Regular all-season and winter tires don't have very broad and deep voids and, thus, are not suitable for driving in mud. In the past, M+S tires had more substantial grooves, but today, when most roads are paved, tiremakers just want to extract as much road grip as possible. Because if they didn't do that and just made the grooves on the tires huge, they would have lost every comparison test, where tires are exclusively tested on paved roads.

2. The S in M+S

The "S" in the M+S classification represents 'Snow.' Snow-rated tires also have distinct tread patterns designed to maintain traction in snowy conditions. The tread design for snow often includes biting edges and sipes, which are tiny slits in the tread blocks.

Additionally, snow-rated tires often use a specific rubber compound designed to remain flexible in cold conditions, improving grip and handling in winter conditions.

Unlike the "M," though, the Snow classification at least means something in these tires. Namely, tiremakers use the designation in their all-season and winter models, both of which are capable of tackling light snow.

Still, there is a huge performance differential between all-season and winter tires when it comes to tackling snow. Even though they carry the same symbol, all-season tires can't come close to winter tires on snow-covered roads. This means that apart from telling you that M+S tires are not summer tires, the rating won't tell how the tires perform.

3. The Implications of M+S

When talking about the M+S rating in particular, it is important to note that it is not tested independently. Any tiremaker can put it on their tires, even those super-cheap Chinese manufacturers. Does that mean the tire will perform well on mud and snow? Of course not. It just means that the manufacturer thinks that these tires are usable on those surfaces.

Now, tires with the Three-Peak Mountain Snowflake (3PMSF) symbol are subject to more stringent testing standards. Notably, these tires should demonstrate at least 110% of the traction of a reference tire in standardized testing conditions. However, the tires are only tested for longitudinal traction, i.e., braking and acceleration – no cornering is involved.

Three-Peak Mountain Snowflake (3PMSF) Rating and M+S Tires

The Three-Peak Mountain Snowflake (3PMSF) symbol is easier to understand than the M+S symbol simply because it necessitates testing. However, it still won't tell you everything about the performance of the tire, and I will tell you why.

1. Understanding the 3PMSF rating

The Three-Peak Mountain Snowflake (3PMSF) symbol is a critical marking on a tire that indicates it has been tested and certified to perform under severe snow conditions. The symbol, depicting a snowflake against a background of three mountain peaks, signifies that the tire exceeds industry-specified snow traction performance requirements.

The test necessary to get the 3PMSF symbol goes beyond the usual visual inspection of M+S tires. The procedure involves accelerating and braking on medium-packed snow and involves the test tire and a reference tire. The latter is designed just to meet the requirements of the test and has a known, standardized level of traction.

For the tested tire to pass the test and gain the 3PMSF symbol, it needs to offer 110% of the longitudinal traction, i.e., braking and acceleration. It is important to note that cornering is not involved, but also that the test doesn't include icy conditions, slush, or extremely cold temperatures. Thus, it is more reliable than the M+S rating, but it doesn't take everything into account.

2. Comparing M+S Tires with 3PMSF Rated Tires

There is no question that having the 3PMSF rating on a tire tells you more about how it performs on snow-covered roads. In other words, on average, a 3PMSF tire will provide you with better traction on snow than an M+S tire.

However, that is not always true. In fact, I can think of many tires with only the M+S symbol that performs better on snow than 3PMSF tires. And the reason for that is pretty straightforward – some tiremakers don't want to pay for the independent testing and instead, use reviews from publications as a way to showcase the superiority of their tires.

One such manufacturer is Continental, a company that doesn't use the 3PMSF on its all-season tires. But regardless of that, in my testing, they casually beat competitors that have the symbol, and sometimes very convincingly. In that sense, you should also never assume that just because an all-season tire has the symbol, it will be better on snow than just about any M+S tire available on the market.

On a side note, all-season tires with the 3PMSF rating are today called all-weather tires. On average, compared to a regular all-season tire, they offer better snow capabilities, though sometimes at the expense of treadlife, dry/wet traction, and comfort.

Factors to Consider When Choosing Between M+S and 3PMSF Tires

Now that we made things clear, you might be thinking – where should I spend my money next? Should I buy M+S or 3PMSF tires? Don't worry, as I have the answers for you!

1. Road Conditions

Before buying a set of tires, you need to consider the weather conditions in your area. Namely, if you live in an area where it doesn't snow frequently during the winter, any M+S tire will do the trick.

However, if you encounter harsher wintry conditions with regular snow, you might want to invest in a set of 3PMSF tires. Again, as I said, some M+S tires will do the job better than their 3PMSF counterparts, but on average, a 3PMSF tire will perform better on snow.

2. Longevity and Wear

Apart from the more aggressive tread pattern with wider and deeper grooves, 3PMSF tires are also made from a softer rubber compound that needs to stay pliable at lower temperatures.

Unfortunately, the softer rubber wears faster, so on average, you will get from 10,000 miles to 20,000 less treadlife if you opt for 3PMSF all-weather tires instead of M+S all-season tires. That is also reflected in the warranty – 3PMSF tires come with shorter treadwear warranties.

3. Comfort and Noise

As far as ride quality goes, there really is not much difference between M+S and 3PMSF tires. However, 3PMSF tires tend to be noisier on average due to the more aggressive tread pattern and softer compound. Of course, there are outliers here; for instance, the Michelin CrossClimate 2, which is one of the best 3PMSF all-weather/all-season tires on the market, is also super quiet on the highway.

4. Cost Considerations

The price is another factor that could influence your decision. Generally, 3PMSF-rated tires tend to be more expensive than M+S tires. That is mainly because manufacturers pay for the 3PMSF test but also because of the more advanced materials usually involved in these tires. Still, investing in 3PMSF tires can be beneficial for those living in areas with heavy snowfall and harsh winter conditions.

The Relevance of the M+S Marking Today

Tire markings can often feel like a secret language, and understanding them can seem like cracking a code. Although once a beacon of assurance for drivers, the relevance of the M+S symbol has been weathered down over time.

These days, it's found on virtually any tire that isn't specifically a summer tire, from all-season to off-road and winter tires. The once meaningful M+S symbol now holds little weight in the decision-making process of tire purchases.

1. Read the Tire's Dedicated Web Page

However, we now live in an age of transparency and easy access to information, thanks to the digital revolution. This evolution has brought about a new approach to purchasing tires, one that calls for a little more research but promises much better results.

The good news is most tire manufacturers are more than willing to share comprehensive details about their products online. Just a simple Google search and click can lead you to a wealth of information! Tire manufacturers typically provide specifications about the type of tire, its optimal weather conditions, and even the materials used in its construction.

For a more detailed understanding, many manufacturers offer spider charts that provide insight into the tire's performance across various parameters – dry, wet, snowy, icy, and off-road conditions. Such charts offer a visual snapshot of the tire's capabilities, making it easier for you to make an informed choice.

2. Read Online Reviews

Furthermore, there are numerous digital publications that tirelessly test tires to reveal their true identity. We also have quite a lot of tire reviews on our website, which will show you a clear picture of how the tire performs across various weather conditions, how comfortable it is, and how long it will last. Combine that with knowledge from people that already own the tire, and you will have all the data you need to make an informed purchase.

Conclusion

It's safe to say that the simple M+S symbol of the past has been overshadowed by the abundance of detailed information that's readily available today. So, the next time you're in the market for new tires, remember, don't just rely on the symbols on the sidewall. Go ahead and delve deeper, do some independent research, read through the tire reviews, and truly understand what each tire has to offer because the right set of tires can transform your driving experience like nothing else can.