Dimension tool shows question mark instead of the length when component closed

anyone have a clue why all I see when I close this component is a question mark instead of the dimension.

The dimension is for the diameter of a circle.

makes it impossible to scale the wheel I am working on to the size I need.

sketchup make 17.1.174 64bit on win 10

Without seeing it we have no way of knowing.
However, the Scale tool allows you to set a specific size.
Start scaling, then type what you want the dimension to be including the unit and hit enter.

With the component closed, all I see is a question Mark for the diameter.

with the component open I can see the diameter

I am trying to scale based on the tire bead seat on the rim as that is a known dimension. so scaling the whole thing based on an overall size isn’t an option.

sorry for the different views. sketchup will not export an image of an open component.

From your screenshots I can’t give you an answer as to why you get a ?

But, as to scaling your wheel, use the tape measure.
With the wheel component open for editing, Click two opposite points on the rim and type the size you want and hit enter, it will ask if you want to resize the active group or component. Say yes and it will scale the whole wheel to fit.

ooh nice. off to try that. thank you