There are some issues with the PDF rendering.
One option is to look for 3rd party renderers - such as Aspose - to see if they have this issue or not. Another is to tweak what you are displaying for instance strip the tab out with a Replace function. You can dynamically increase the Left Padding property by detecting if there was a tab to over come this.
So the Value would be something like (you'll have to check exact syntax);
=(Fields!MyField.Value).Replace(vbTab, "")
And the Left Pad property would be something like;
=IIf((Fields!MyField.Value).IndexOf(vbTab) = 0, "1pt", "4pt")
You can add to these expressions to test for multiple spaces too.