Can't pass CornerRadius through TemplateBinding/TemplatedParent - wpf

Question

I have a style for Buttons and now I want to apply it to RadioButtons, except that where a normal Button has a CornerRadius that is a single number (each corner is the same) I want to render the RadioButtons with different corner radii, like this:
I use a custom ControlTemplate for Button as well as a style:
<ControlTemplate TargetType="{x:Type ButtonBase}" x:Key="ButtonTemplate">
<Border Background="{TemplateBinding Background}"
Width="{TemplateBinding Width}"
CornerRadius="22.5"
BorderThickness="{TemplateBinding BorderThickness}" BorderBrush="{TemplateBinding Foreground}">
<TextBlock FontSize="14" FontWeight="Bold"
TextWrapping="Wrap" TextAlignment="Center"
VerticalAlignment="Center" HorizontalAlignment="Center" Margin="30 0"
Foreground="{Binding Foreground, RelativeSource={RelativeSource TemplatedParent}}"
Text="{Binding Content, RelativeSource={RelativeSource TemplatedParent}}"/>
</Border>
</ControlTemplate>
<Style TargetType="{x:Type ButtonBase}" x:Key="MainButton">
<Setter Property="Foreground" Value="{StaticResource IntBlue2}"/>
<Setter Property="TextBlock.Foreground" Value="{StaticResource IntBlue2}"/>
<Setter Property="BorderThickness" Value="2"/>
<Setter Property="Background" Value="Transparent"/>
<Setter Property="MinWidth" Value="132"/>
<Setter Property="Template" Value="{StaticResource ButtonTemplate}"/>
<Style.Triggers>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="Foreground" Value="LightSlateGray"/>
</Trigger>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Foreground" Value="#66CDFF"/>
</Trigger>
</Style.Triggers>
</Style>
And I have a style for RadioButton that uses the Button template
<Style TargetType="RadioButton">
<Setter Property="Template" Value="{StaticResource ButtonTemplate}"/>
<Setter Property="Background" Value="Transparent"/>
<Setter Property="Foreground" Value="{StaticResource ForegroundPureWhite}"/>
<Setter Property="BorderThickness" Value="2"/>
<Style.Triggers>
<Trigger Property="IsChecked" Value="False">
<Setter Property="Foreground" Value="{StaticResource DisabledGrey}"/>
</Trigger>
</Style.Triggers>
</Style>
Everything above works, until I want the custom CornerRadius for each RadioButton.
I've tried CornerRadius="{Binding CornerRadius, RelativeSource={RelativeSource TemplatedParent}}" inside the Border in the ControlTemplate, and <Setter Property="Border.CornerRadius" Value="22.5"/> inside the MainButton style, but it doesn't work (it doesn't apply the radius).
Binding CornerRadius="{TemplateBinding CornerRadius}" to the border in the template doesn't even compile, and setting CornerRadius on a Button or RadioButton, through the control tag or through a setter in the style, also doesn't compile.
How do I use one template, but different CornerRadius in each style or instance?

Answer 1

A ButtonBase has no CornerRadius property that you can bind to but you could use the Tag property:
<ControlTemplate TargetType="{x:Type ButtonBase}" x:Key="ButtonTemplate">
<Border Background="{TemplateBinding Background}"
Width="{TemplateBinding Width}"
CornerRadius="{Binding Tag, RelativeSource={RelativeSource TemplatedParent}}"
...
<Style TargetType="RadioButton">
<Setter Property="Tag" Value="22.5" />
...
</Style>
<RadioButton ... Tag="0" />