I went with yes - using rubber reinforces the idea that it's a miniature facsimile/replica of a larger vehicle, and it's a kind of indicator of 'care'/'thought'/'effort' being put into a figure. That said, I don't mind if solid plastic tyres are used as a cost-saving measure - it would've been nice if rubber tyres were used on the Human Alliance series or RotF leader-class Optimus and its derivatives, but it's hardly a deal-breaker (for me at least).