Steering spline telescoping shaft, and steering device

A spline telescoping shaft is provided with an inner shaft including a male spline, and a cylindrical outer shaft including a female spline. The surface of at least one of the splines is provided with a resin coating. Profile shift coefficient e, the number of teeth Z, module m, reference pitch diameter PCD, the tip diameter d1 and root diameter d2 of the male spline, and the tip diameter D1 and root diameter D2 of the female spline have the relationships according to expressions (1) to (8): m(Z + 4) > d1 > m(Z + 2) (1); mZ > d2 > m(Z - 1) (2); m(Z + 4) > D2 > m(Z + 2) (3); mZ > D1 > m(Z - 1) (4); D2 > d1 (5); D1 > d2 (6); PCD = mZ (7); and 0.4 < e < 1.1 (8). 种用于确定安装车轮上并且在地面上滚动的轮胎的潜在附着力的方法，包括下列步骤：?根据具有可变的和已知的附着力的在路面上的所述轮胎的预定滚动条件的来评估轮胎的滚动半径的变化，为了形成实验数据库，?基于所述实验数据库，通过确定将潜在附着力(μ)联系到滚动半径(RRt)和车辆参数的函数，来建立潜在附着力(M)的评估模型，在轮胎滚动时确定滚动半径(RRt)，并且通过应用所述模型(M)并根据车辆参数来评估所述轮胎的潜在附着力(μ)。