When selecting fabric for track pants, you must prioritize GSM (Grams per Square Meter), which typically ranges from 200 to 350 GSM depending on the desired thickness. The material composition is critical; look for blends like 95% Polyester and 5% Spandex for durability and stretch, or Cotton-Polyester blends for a softer, breathable feel. Additionally, verify the moisture-wicking capabilities and colorfastness (Grade 4 or higher) to ensure the fabric maintains its appearance after multiple washes.