What are Low Profile Tires? (The Importance of Tire Aspect Ratio)

Tire profile is an interesting topic. Not only does it affect the vehicle's aesthetic, but it also has correlations to its performance. The debate of low profile vs high profile tires has been a hot topic over the years.

The meaning of a low profile tire has drastically changed over the decades, which resulted in the low profile tires we know today. But, how did the tire market get to low aspect ratio models, what do they offer, and why are they so liked? Let's discuss it!

Why Are All Season Tires So Popular?

From the higher aspect ratio tires ever to exist to the low profile tires of the modern era, tire technology has come a long way. Let's speed run how low pro tires came to be.

Around the 1920s, most tires manufactured had a 98% aspect ratio. Compared to today's standards, those sidewalls were huge. This number decreased by the 1970s to around 70% as tires with a 70 aspect ratio became more popular. Nowadays, 65-55 series tires are considered to be normal touring models.

In 1968, when Pirelli introduced the first 70 aspect ratio tire to the market. Back then, this was considered to be a low profile tire. Over the years, the definition of low profile tires has changed a lot. So, what is considered a low profile tire today?

What Are Low Profile Tires?

Low pro or low profile tires are tires manufactured with thinner sidewalls. As their name suggests, they sport shorter sidewalls compared to high profile tires. Their aspect ratio, the sidewall section width vs tread width in percentages, is lower.

In other words, high profile tires will have a wider footprint compared to thin tires with the same aspect ratio. Low profile tires are considered to be tires that have aspect ratios lower than 50. These tires will have wider footprints and skinnier sidewalls.

What Is the Aspect Ratio of a Tire?

No matter whether you are looking at low profile or high profile tires, they will have aspect ratios. It is an important part of the tire size. How to tell what size tire you have?

Let's take P245/40r17 as an example to talk about the aspect ratio, without creating a full tire size guide. What number determines the width of a tire? The first one. The tire aspect ratio is the second number, which represents the sidewall height in percentages compared to the tire width. This number determines whether the tire is a low profile one or not. Basically, the higher the aspect ratio, the taller the sidewall.

In this example, the tire sidewall is 40% of the 245 widths. Therefore, since the width is 245 mm, the sidewall height will be 98 mm or 3.85 inches, which is a low profile tire size.

Low Profile Tires vs Regular Tires

The difference between low profile tires and regular (or higher profile) tires is the aspect ratio. Tires with higher than 50 aspect ratios are high profile tire sizes, while lower than 50 are slim tires.

Can You Put Regular Tires on Low Profile Rims?

If you wish to mount regular tires back on your vehicle, you will need to change the rims as well. This is because it is extremely difficult to find rims that accommodate regular, high profile tire sets. These tires are narrower compared to low aspect ratio tires, and they will be too short on low profile rims.

How to Calculate Sidewall Height?

If you are thinking about mounting low profile tires on your vehicle, math is unavoidable.

Changing low profile tires to high aspect ratio tires, and vice versa, requires some calculations on our parts. Let's take 225/35R18 and 275/35R18 tires as an example (we are not saying these sizes are interchangeable, we are just using them to show how the calculations work). These two sizes have the same aspect ratio, but due to the difference in their tread width, their sidewall height will differ.

So, if the 225/35R18 has a tread that is 225 mm wide and its sidewall is 35% of that, then the height of the sidewall will be 78.8 mm or 3.1 inches. We get to this number by multiplying the width by the aspect ratio as a decimal. This makes the 275/35R18's sidewall height 96.3 mm or 3.8 inches.

Tire Aspect Ratio Comparison

Even if tires have the same aspect ratio, if their width is not identical the sidewall height will not be the same. But, is it really that important? Does aspect ratio matter on tires?

The difference between the sidewall height of the previously mentioned two tires is 0.7 inches. This might seem insignificant when it comes to tire profiles, but it is enough to cause vehicle and performance issues. From problems with the suspension system to changes in the vehicle's controllability and comfort, it will affect it all.

However, when looking at various tire sizes, the sidewall size will be noticeably smaller. These thinner tires typically have a wider footprint compared to their high profile counterparts. In other words, the difference between 195/65R15, 275/40R17, and 295/25R20 tires will be eye-catching.

The aspect ratio is crucial as it determines the overall height of the tire. If the tires are the incorrect size, they can easily result in structural, mechanical, and driving problems.

Low Profile Tires Pros and Cons

So, you found cheap low profile tires, but you are not sure if changing to them is a good idea. In a perfect world, anything we like works perfectly without issues or drawbacks. But, sadly, as with all things, low profile tires have their ups and downs as well.

If your vehicle can work with low profile tires, there are still some positive and negative characteristics you should consider. In the same way, you will gain excellent performance, fuel efficiency, and a sportier look, there are some characteristics you will need to sacrifice.

Benefits of Low Profile Tires

Low profile tires are a great choice for any sports car, as long as the correct size is chosen. But, what do low profile tires actually offer? A better grip is just the beginning.

Better Performance

Skinny tires feature wider tread areas. This results in a larger road contact patch, which is combined with stiffer sidewalls in order to ensure better handling and more traction. It is more prominent and noticeable during the high speed performance of low profile tires when sharper and quicker steering responses are necessary.

Thanks to this, low pro tires also enhance their braking and cornering capabilities. The shorter sidewall creates better stability by eliminating its flexing. As a result, effortless cornering and maneuvering are guaranteed. On the other hand, bigger rims give space for larger braking elements that can help shorten the vehicle's braking distance.

But, do big rims damage suspension? Technically, no. The issue comes when drivers switch to larger wheels without taking the sidewall height into account.

The Ideal Structure for Run Flat Low Profile Tires

Why are low profile run flat tires more ideal compared to their high profile counterparts? The answer is simple.

The psi for low profile tires is lower to start with. For this reason, manufacturers can manipulate tire technologies more easily. Additionally, as their sidewalls are shorter, simpler reinforcements can be used in order to maintain the ideal tire shape after air pressure loss.

Of course, not all low profile tires are run flat. Therefore, how to know if tires are run flat or not? Run flat tires, whether they are low or high profile tires, are marked as such by the tire manufacturer. But, they all have one thing in common: after the loss of air pressure, they offer a 50-mile, 50-mph drive.

Fuel Efficiency Boost

Thanks to their narrow sidewalls that eliminate flexing, the wider footprints, and even the reduced weight of alloy rims, low profile tires generate less rolling resistance. These elements all work together to minimize the pressure generated while the tires are in motion. As a result, the vehicle's fuel intake and CO2 emissions are significantly reduced, even during its high speed applications.

Of course, the intensity of the rolling resistance greatly depends on the type of tire we are looking at. Off-road tires will always generate more pressure than even used on-road tire models. Still, lower profile tires can help improve fuel economy in all instances.

Low Profile Design for a Sporty Look

Rims with low profile tires give off a specific aesthetic that is undeniably eye-catching. This look has been around for a couple of decades and it is not going out of vehicle fashion any time soon. Due to the high demand for such tune-ups, car manufacturers provide low profile tires on their Original Equipment, or OE, tire lists. This can help drivers choose the correct low profile tire variations for their vehicles.

Cons of Low Profile Tires

Before you run to mount low profile all season tires on your car, there are a few more questions we will answer. Namely, "Do low profile tires wear faster?" and "Do low profile tires ride rough?"

The short answer to both of them is yes. But, let's take a look at what else car owners need a look out for when using summer, winter, or all season low profile tires on their vehicles.

Low Profile Tires Ride Rough

Lower sidewall profiles result in bumpy tires - and thus a bumpier ride. This is because wider sidewalls are able to absorb the shock of driving, unlike thinner tires. So, do wider tires ride better? Not necessarily.

How intense the driving vibrations will be in the vehicle's cabin is determined by the vehicle's spring rate. The tires, the suspension system, and the seat cushions all contribute to this calculation. Yet, the tires provide the most in order to decrease road vibrations.

As a result, switching to low pro tires will instantly diminish your driving comfort. However, changing the suspension can help minimize this impact.

Vulnerable to Tread and Rim Damage

Do low profile tires lose air faster? Yes, because low profile tires do not need as much air, their loss of psi is rapid and will leave the tire flat in an instant (unless it is a run flat tire). Sadly, low profile tires do not offer protection against external damage. Tires with lower aspect ratios are more prone to experience damage and they do not offer wheel protection either.

So, how long do low profile tires last? The diplomatic answer is that they last for about 40-45,000 miles, depending on the tire brand you purchase. But, in reality, if these tires experience damage, they will most likely need to be changed. While their tread areas can be patched and repaired, often the damage is not repairable and it can extend to the wheel.

Low Pros Wear Faster

Low pro models are also low tread tires for various reasons. In order to provide a better grip, these tires are manufactured from a softer compound. The downside of this compound blend is that they wear faster as its materials are softer.

Furthermore, larger loads, higher speeds, aggressive driving, and harsh braking all contribute to premature and irregular tire wear patterns. While there are certain things drivers can do to prevent such issues, low profile tires will still have shorter service lives.

Not For Uneven Surfaces

The stable, but stiff tread of low profile models is perfect for high speed highway applications. Yet, you will find issues on uneven roads. Any off-road performance is out of the question, as the contact patch will not generate traction on gravel or dirt roads.

But, are low profile tires good in snow? No, using low profile tires in snow is not a good idea. While low profile snow tires exist, their snow and ice traction is basically useless. They lack the tread depth and compound durability to offer a secure drive. Be careful when driving on low profile winter tires.

They are not good in snow. So, are low profile tires bad in rain as well? It depends. If the tires feature a directional tread pattern, that is able to channel water from the footprint, they will offer decent hydroplaning resistance. The problem comes when their tread pattern is not optimized, because then hydroplaning will occur, especially during its high speed drive.

Louder Than Regular Tires

Are low profile tires good for long trips? Well, are you willing to sacrifice driving comfort?

While low profile tires will get you where you need to be, their performance will depend on the road conditions. Still, as they come with wider footprints, they will generate more road noise which might be a problem for some drivers.

Most road noise is created when airwaves travel through the footprint, but the tire pressure for low profile tires and their tread vibrations also contribute. The combination of these issues results in the white noise heard while the tires are in motion.

How Low Is Too Low to Drive on a Tire?

The lowest aspect ratio tire ever developed was a Kumho model in the size 385/15R22. It was introduced at the 2008 SEMA Show, or Specialty Equipment Market Association. But, this tire will not work on the majority of the low profile cars available on the market.

When thinking about how to make your car look sporty, low profile tires are often the first answer. Yet, it is important to know how low you can go and that will depend on your vehicle's specifications. Another factor to consider is psi as even when talking about low profile, tire pressure is crucial.

As the low profile tire size is smaller than normal tires, these sets will be able to hold less air pressure as well. Therefore, depending on the size of your low profile tire set, you can go as low as 14.5 psi, with the average levels sitting around 30 psi. Typically, anything below 20 psi is a flat tire, but with low pro tires, these levels are lower.

Are Low Profile Tires More Expensive?

Yes, low profile tires are more expensive than conventional tires. Not only that, but their upkeep also tends to have a higher cost. This is due to their lowered damage resistance we have mentioned before.

When talking about the cost of low profile tires, prepare to spend more. Typically good-quality low profile tires cost between $100-$300. However, for some low profile tire sizes, cheaper options are also available.