Cutting The Guesswork From Tire Development

The best tires for triathlon

TPI stands for threads per inch, the quantity of threads per in used to construct the tire’s backbone, its casing. It is widely assumed that a tire with high a TPI count is better than a low TPI count, but Wheel Energy has helped Specialized find that while that may be true for some road races tires with moderate TPI count, somewhere between 60 and 120 TPI, are ideal for triathletes.

“There is a misperception,” says Vorm Walde. “60 TPI can be fast.”

Although it is true that tires with high TPI count are more supple and lighter than tires with fewer threads, suppleness and weight aren’t the most important attributes for a triathlon tire. To get from T1 to T2 as fast as possible, a tire should be designed for low rolling resistance and good puncture protection. Those two characteristics are actually facilitated by moderate a tire casing with a moderate thread count, between 60 and 120 TPI, not an ultra-high TPI tire.

Wolf says, “The Specialized Turbo Pro (120 PI) is a more appropriate tire [for triathlon] than the S-Works [Turbo Tire (220 TPI)]. The amazing thing about that statement is that the Turbo Pro is cheaper than the S-Works Turbo. If you want a very lightweight tire, 220 TPI achieves that. For all-around riding or racing, I would always go for 120 TPI at the most. [That construction] is more robust, we have weight, rolling resistance and puncture protection. The thicker the fiber, the more cut resistance. 30 TPI is the most cut resistant. With 60-120 TPI, the fibers are laid close enough that it is not so easy to stick a nail through this fabric but the fabric is cut-resistant. At 220 TPI the fibers are so thin, it’s pretty easy to cut the sidewall,” says Vorm Walde.