Tires 101: All about Tread (not Thread)

Tread is the tire feature that gives your tires traction

First things first: it's tread, not thread. Tread is that groovy rubber surface of a tire that’s in constant contact with the road. Thread is what you use to sew fabrics with. 

WHAT IS TREAD FOR?

As you may have surmised, the tread is responsible for keeping your tires firmly connected to the road, and by extension, your vehicle as well. To do this, it needs four basic parts – the rib, lugs or blocks, grooves, and sipes.

A lot of money, R&D, and technology went into the formula to make and design these parts of the tread, but don’t worry, I won’t make you suffer through it. Just like its simple names, their functions are very basic as well. Collectively, these work together to keep you safe while driving on the road by doing the following:

-Increase traction and grip

-Disperse water

-Improve braking distance

-Provide maneuverability and steering

-Reduce road noise

-Cool the tires

Remember all of the above the next time you take a gander at your tires and see that the tread is worn out, or when you think of scrimping on really cheap tires.

FOUR COMMON TIRE TREAD DESIGNS

Treads make tires look trendy with stylish outlines but these aren’t to be mistaken as designs – these are called patterns. There are four of them and each serves a specific purpose with specific advantages and disadvantages. For this article, we'll look at passenger car tires. 

SYMMETRICAL MULTI-DIRECTIONAL patterns are the most common as these are found on most passenger cars. It gets its name because the outer and inner parts are a mirror image of the other, or symmetrical. It can be mounted and rotated in either direction, which is why it’s also known as multi-directional pattern.

Such tires are not optimized for performance; these are meant to be affordable and functional and generally mounted onto your average 4-door sedan or hatchback.

Pros: Quiet ride, fuel-efficient, high durability, good dry grip, typically cheaper

Cons: Generally not high performance

Overall: General purpose everyday tires

DIRECTIONAL or UNI-DIRECTIONAL patterns can also be found on passenger tires, but typically these kinds of tread patterns are more common on higher-end cars. It’s known for an arrow-like tread design and is meant to roll only in the direction it’s pointing. These tires are generally optimized for higher levels of grip and water clearing, and typically use softer rubber compounds to deliver a high level of traction. The downside is faster wear, and one must also check if the tire is mounted correctly.

Pros: Rapid water dispersion, great traction & grip at high speeds

Cons: Expensive, short lifespan, more noise, fuel efficiency

Overall: A good upgrade from standard tires

ASYMMETRICAL uses two different patterns on one tire, hence the name. The tread on the inner half is designed to prevent aquaplaning while the outer half is made to increase grip and traction. Because of its versatility and price, it’s mostly used by high-performance cars. Also, it uses a soft rubber compound so expect faster wear and tear.

Pros: Superior handling, cornering stability (wet and dry), quiet

Cons: More expensive than symmetrical tires, short lifespan

Overall: Great touring tires

DIRECTIONAL-ASYMMETRICAL treads aren’t very common and are more often used by supercars. It combines the elements of both tread patterns and has a V-shaped groove that’s a little off-center.

Pros: Maximum handling (wet and dry)

Cons: Hard to find, very expensive, short lifespan

Overall: Generally more common on exotics

WHAT IS TREAD DEPTH

That’s the measurement of your tire's tread, from the surface all the way down to the deepest groove. New tires start with an average of some 8 mm to 9 mm. This gets worn down as you drive.

Make sure it doesn’t go below 2 mm. If it does, replace the tires. Most countries keep the tread minimum at 1.6 mm but do you really want to risk life and limb for an extra 0.4 mm?

Without adequate tread depth, your tires won’t be able to provide grip for effective road contact, traction, acceleration, and braking. It also won’t be as effective in dispersing water on rainy days or when the roads are wet. When this happens, you could lose steering control and slide straight to a pole or worse, a shed full of people.

The most accurate way to measure tread depth is with a tread depth gauge. Stick the short end into the shallowest groove and the reading will pop out on the other end. You can also use a vernier caliper.

Another way is by doing the 25-centavo test. The modern 25 cents measure 20mm in diameter. If you stick it in the groove and can’t see the word Katmon (the name of the flower featured in the coin), time to replace the tire.

Having made it all the way here, we hope that from now on you’ll look at tire tread in a whole new light because you now know it really isn’t fancy-schmancy tire art. It’s there for your safety and those around you, motorists and pedestrians.