Assessment of the Influence of Tire Inflation Pressure on the Forces Applied to a Commercial Vehicle’s Steering System

One of the major challenges on the automotive industry is how to delineate a set of representative and real road loads, for reliability and efficiency during the validation stage on the development process. While several previous studies presented evaluations and results of the tire inflation pressure influence on the fuel consumption, driver comfort, vertical load and braking and handling performance, the objective of this work is to assess the influence of the tire pressure on the forces applied to a commercial vehicle’s steering system. In this regard, the steering link-rod of a truck has been instrumented and used as a load cell, in order to quantify the forces applied to the vehicle’s pitman arm on different tire inflation pressures. The measurements were performed in a static dry-park (lock-to-lock) maneuver and by decreasing the tire inflation pressure of the vehicle’s front loaded axle (6 tons) from 110 psi (7.6 bar) to 50 psi, in steps of 10 psi. Mainly for the inflation pressures below 80 psi, the results suggested a great influence of the tire inflation pressure on the forces applied to the vehicle’s steering system. Compared to the force on the tire’s nominal pressure value (110 psi), the increase of the force on a low tire inflation pressure (50 psi) was up to 14%. Although further studies are necessary, the obtained results are an important output for design and test engineers, who should consider these different scenarios in calculation, simulation and test schedules of the steering system.