60 TPI or 120 TPI are common labels on the sidewall of MTB tires. They describe the tire casing.
And which one you use actually makes a big difference – I wish I had known about TPI earlier to pick better tires for my mountain bikes.
Key Takeaways
TPI stands for threads per square inch.
A tire casing is made of individual nylon threads woven together. And TPI describes how thin the threads are and how many are used in one square inch of nylon cloth
The higher the TPI number, the smaller the individual threads are. Which makes the tire casing more compliant, thinner and softer.
120 TPI and 60 TPI are the most common casing options you can choose from in mountain bike tires.
Up to 320 TPI is not uncommon in road cycling because there they use much thinner threads to produce a tire that is as lightweight as possible while still somewhat comfortable to ride on hard concrete.
60 TPI vs 120 TPI
120 TPI tire casings basically use twice as many nylon threads, which are each half as thick compared to 60 TPI tires.
This means 120 TPI tire casings are thinner, softer and lighter than 60 TPI.
60 TPI are stiffer, more puncture resistant and handle big impacts better.
120 TPI is better for Cross Country, Trail and Enduro, where weight and comfort are important.
60 TPI is better for high-impact riding like Downhill and Freeride, where puncture resistance and cornering stability are key.
So 120 TPI is usually more expensive, but not always better. It depends on what you need out of your tire. You could run a 60 TPI XC tire, but really shouldn’t run a 120 TPI for hard DH riding – even if it has some puncture armor inserts.
A thicker casing is the best puncture protection you can have.
The downside to having bigger, but fewer threads, is the loss in compliance with the ground. The stiffer casing simply can’t conform as well to the ground as a 120 TPI tire can.
There are also dual-ply casings (like Maxxis DoubleDown) that use two layers of 120 TPI (rarely 60 TPI) for the best of both worlds.
High TPI MTB tires often need additional puncture-resistant inserts to prevent flat tires.
Note: this has nothing to do with the rubber compounds of the tire tread – which can be soft or hard regardless of casing.
Quick little history
Bike tires used to be manufactured from cotton thread back in the day.
Some high-end road tires still are because of the ride quality that only cotton can offer.
A major downside of cotton thread used in a tire, that has to endure a lot of abuse, is – you might have guessed it – durability.
This is why bike tire manufacturing has moved into using nylon thread.
