I have a aluminium. MK IV 1993. I researched this extensively before ordering from Avon as I didn't want he car looking undertyred. I went to the trouble of making precise hardboard templates and attached them to my 15" wheels and checked the rolling clearance empirically in all steering positions.
I concluded and fitted with no problems.
Front Avon ZZ 225/65/R15
Rear Avon ZX 275/55/R15
There are great benefits to this combination, in as much as both front and rear are the same diameters and look great. The front 65 profile as opposed to the commonly fitted 60 is a full inch bigger in diameter, which will give you more ground clearance and as well as a more period high profile look.
There are no wheel arch rubbing issues whatsoever and my car being late model, did not require bending the steering arms. I do more mileage than most on my MK IV, covering 6000 miles last year all over Europe.
I can only speak for my car. Don't be tempted to fit 295 on the back, they will be too tight.
Order direct from Avon and ask for competition discount.
I'm near London if you want to see for yourself, or you can borrow the templates if you want.