The 17 will rub slightly on a 25 even if you have the correct 205/45/17 tyres - the ZR steering rack had restrictors to reduce the steering travel to prevent rubbage, which is why the ZR has such a poor turning circle.
You could replace your rack with one from a ZR, or alternatively make and fit a smooth wear plate to the area of the arch that the tyre rubs on to alleviate any damage to the tyre - you will need to do this to pass an MOT test as any signs of a tyre fouling a part of the vehicle and resulting in wear/damage to the tyre will be a fail (Major).
The MOT inspection manual has this to say in regard to tyre to body contact and the use of a lock stop/wear plate:
Evidence of a tyre contacting a part of the vehicle, such as due to tyre flexing or suspension movement, is not considered to be a defect. A vehicle should only be rejected if the tyre is fouling a part of the vehicle at the time of test.
Some vehicles have lock stops comprising rubbing pads on the body that the front tyres may contact on a full lock. These are acceptable if they are properly maintained so that they do not damage the tyres.