You can set custom range for both axes by turning off the AutoScale property and providing MinValue, MaxValue and Step like this:
this.radChart1.PlotArea.XAxis.AutoScale = false;
this.radChart1.PlotArea.XAxis.AddRange(10, 20, 1);
For more information you can refer to our help topic
the Telerik team
Q1’11 SP1 of RadControls for WinForms is available for download
; also available is the Q2'11 Roadmap
for Telerik Windows Forms controls.