A method of modeling a tire includes providing a tire having a first tire design, rotating the tire under a vertical load, and measuring a plurality of forces at a plurality of selected conditions. The method further includes using a computer to plot the plurality of forces against the plurality of conditions, using the computer to plot a plurality of moments against the plurality of conditions, and using the computer to fit a first force curve to the plurality of plotted forces at the plurality of conditions, such that the first force curve is asymmetric. The method also includes using the computer to fit a first moment curve to the plurality of plotted moments at the plurality of conditions, evaluating the first force curve and the first moment curve, and making a second tire design based on the evaluation of the first force curve and the first moment curve.