There are some issues with the appearance of the gauges in RTL mode. They vary across browsers.

An easy fix is to add a CSS class to each of them and force direction: ltr:

<telerik:RadRadialGauge CssClass="rtlFix" ID="radialGauge1" runat="server" Width="272px" Height="272px">
    . . . . .
</telerik:RadRadialGauge>

.rtlFix
{
    direction: ltr;
}

If you need to swap the places of the min and max value the Reverse property of the Scale inner tag must be set to true.