grober
MB Master
Obviously the tyres would have to to be road/MOT legal and best with a decent element of tread left to simply not draw attention to their condition. Provided they meet the same speed and load rating as the originals I doubt being MO rated will matter unless specifically mentioned in the contract. If the dealer comes the "old soldier " about it a quick perusal of the tyres on their current MB approved used stock on the forecourt might strengthen your position? A decently shod car should be fine. A car on cheap Chinese Ying tong diddle I po ditchfinders down to their last couple of mm will inevitably draw attention?