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Choosing bike tires can be a confusing business. You have to ask yourself what you really want from them, first of all.
Three main qualities define a bike tire: puncture resistance, speed, and comfort.
Short of poring over online reviews, one way you can guess at a bike tire’s attributes is to study its TPI specification.
This article tells you all you need to know about bike tire TPI and how it can increase your enjoyment of cycling.
What Does Bike Tire TPI Mean?
The TPI acronym is short for “threads per inch”.
Bicycle tires have a tire “casing”. This is the main body of the tire that lies beneath the exterior tread. The casing is constructed with nylon, cotton or even silk threads.
TPI describes the density of these threads, which are laid diagonally in rubber-coated layers.
Nylon casings have fewer threads per inch than cotton or silk and are by far the most common in tires. These nylon casings are vulcanized into the rubber, thus fusing the components together.
Video: How Vulcanized Bicycle Tires Are Made
Cotton and silk casings are found in handmade “clincher” tires and tubular tires. The latter are a sealed tire with a built-in latex tube. Tubeless tires are a form of clincher.
Rather than being “cooked” into rubber, cotton and silk casings are bonded to a separate vulcanized rubber tread, so the two elements are discrete.
Now we know this, what’s the significance of TPI or threads per inch?
Does Bicycle Tire TPI Matter?
TPI definitely matters in a tire, as it gives you a vital clue as to how a bike tire might perform or what the ride quality is like.
As you may have guessed by now, a high TPI is generally a good thing. Unfortunately, it’s a little more complicated than that.
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Thinner Threads = Less Rubber
The more threads there are per inch in the casing, the thinner those threads are, and the less rubber is necessary to envelope them. And that will mean a lighter, faster, plusher, grippier, more flexible tire.
Thinner threads in a tire usually mean a “denser weave” and create a supple tire, but it is possible to have thin tire threads in a looser weave. This makes for a suppler tire still. It’s usually safe to assume a high TPI trumps a low TPI performance-wise.
Video: The Value Of TPI And Thread Density
Layers: A Vital Statistic
Tire casings are usually made with two or three layers. If there are two, the tire will be suppler, hence more comfortable, grippier and faster. Three layers make the tire stiffer and less flexible, though with the right compound it may still be fast.
A vital element of tires that muddies the waters of TPI is the tire compound. This is the blend of materials used in the rubber, which affects most properties of a tire.
As a result, a vulcanized tire with an advanced compound may be faster than a handmade tire with a higher TPI and lesser tread compound.
Common TPI Numbers Used in Bikes Tires
If you start looking at TPI in bike tire specifications, you’ll see a wide range of numbers. Higher numbers are normally the sum of two or three layers, whereas low numbers are likely to be “per layer”.
If there’s a standard TPI in bike tires, it’s probably 60 TPI. You’ll see this thread count in many budget mountain bike, road, gravel, and urban commuter tires.
Because the threads are relatively thick in this tire, there is also more rubber in it, which theoretically makes it more puncture resistant. A 60 TPI tire leans more towards durability than performance.
A 120 TPI tire is likely to be lightweight, fast and moderately supple. However, these properties are affected by other tire attributes, like the strength or thickness of any puncture-resistance belt.
This is an “honest” TPI if you like, where the manufacturer has chosen to advertise the weave density per layer rather than use multiplied layers for marketing purposes. There may be two or three 120 TPI layers.
Several high-performance Continental tires have a 110 TPI but are advertised as 330 TPI because of the tires’ three layers. (In fairness, Continental makes this clear if you dig into the specs.)
Many vulcanized tires have an advertised 180 TPI specification, though in reality this is usually three layers of 60 TPI. This is fine, so long as you know you’ll be getting a non-performance, heavy, everyday tire that is probably durable.
320 to 350 TPI
Supple “open tubular” style tires from brands like Veloflex and Vittoria typically have a stated TPI of around 320 to 350. They use an ultra-fine Corespun cotton and aramid casing and offer sublime ride quality.
These tires often have two layers. Thus, a 320 TPI tire has 160 TPI per layer in reality. At this point, the ride is plush enough to surpass tubeless tires for comfort. Rolling resistance is low to extremely low. A downside is vulnerability to sidewall cuts.
60 TPI vs 120 TPI: Which Is Better?
The non-standard way TPI is quoted by manufacturers means you can’t always compare like with like. But you can boil it down quite well by asking: which is better out of 60 TPI and 120 TPI? Most tire casings are in one of these two ballparks.
A 60 TPI tire is likely to be inexpensive, durable and puncture resistant. The possible downsides include weight, inflexibility, high rolling resistance (hence relatively slow) and mediocre grip. None of these things stop you getting fit.
If you’re looking for a practical commuting tire, 60 TPI is a decent choice.
A 120 TPI tire will be lighter, more flexible, more comfortable, faster, and grippier. Downsides include the higher price, less puncture resistance and shorter lifespan.
For a high-performing training or racing tire, 120 TPI makes much sense.