Your mechanic is "right" Johann, -"driving is bad for your car".
-Just park it in a dry shady place, -and it lasts forever... [|)]
Your mechanic can just as well tell you that driving up slope is bad for your gearbox.... and driving upwind is therefore equally bad!
Bigger tires usually cause more wear on brakes, hubs and steering but gearbox life has more to to what happens in front of it -ie engine, clutch and how you shift.
Higher gearing (=bigger tires) makes it necessary to get some more torque out of the engine (or downshift and rev faster) -and therefor into the gearbox.
If the gearbox is the right one for the engine that should not be a problem.
And on non turbo 240D and 300D, -"pedal to the metal" is normal setting anyway.
