WTB KOM Tough i25 Rim - 29", TCS Tubeless, Disc, Black, 32H. KOM Tough rims are extruded from top-tier AL 6069 alloy to provide utmost durability at a reasonable weight. WTB's I-Beam construction has evolved to further reinforce the rim with dual support beams that provide increased strength and stiffness for the world's most aggressive riders.