The Aspen ST is an ultra-low-profile race tire designed primarily for short track XC use. Sometimes referred to as the “Fastpen,” this tire is sure to give any racer an edge in dry conditions. Details Category: XC Race Recommended use: Dry XC trail conditions Recommended Installation: Front or Rear Model Highlights: 3C MaxxSpeed 120 or 170 Team Spec TPI casing EXO puncture protection Tubeless Ready Weight: 29 x 2.25", 120 TPI: 670 grams 29 x 2.25", 170 TPI: 610 grams 29 x 2.40", 120 TPI: 750 grams 29 x 2.40", 170 TPI: 685 grams Tire Tech 3C MAXXSpeed: The new MAXXSpeed is a top-shelf rubber compound for XC racing. It’s a high-silica content compound that reduces rolling resistance while also enhancing wet traction. Compared to the previous 3C MaxxSpeed, the new compound has approximately 25% less rolling resistance in a lab setting (using the same tread pattern, construction, and tire pressure). In a real-world setting, our testing shows the new compound can save up to a minute over the course of a 90-minute race. EXO: EXO is a cut- and abrasion-resistant material added to the sidewalls of many Maxxis mountain bike and gravel tires. This densely woven fabric is lightweight and highly flexible, ensuring that the tire's performance remains unaffected. Choose EXO Protection for enhanced durability for gravel, XC, and light-duty trail riding. Tubeless Ready: Tubeless-ready tires provide the rider with many benefits: the ability to run lower air pressures, which improves traction; lower rolling resistance when compared to a tube-type tire; and less chance of flatting because there is no tube. Tubeless-ready tires are denoted by the letters “TR” on the sidewall. Tubeless-ready tires must be mounted to tubeless compatible rims and require the use of a liquid sealant to maintain pressure. Liquid sealants have the added benefit of sealing small punctures. Be sure to check your sealant regularly and refresh as needed, as it will dry out over time. Pick up an extra bottle of sealant here . Liquid sealants should only be used in the following types of tires: tubeless road, tubular, and tubeless-ready. Using liquid sealants in any other Maxxis tire will void the warranty.