17" Wheels

Thank you for the information. Appreciated.

Will have to put my thinking cap on!!

Just try to think about off set on wheel shown by (ET +or-)
You need to be at ET 0 but +5 or -10 will be just fine 
So if you where using a kia serento wheel with off sett ET43 then a 50mm wheel spacer will 
put you at ET-7 in simple terms now your wheel will stick out to the arch by 7mm  

Have decided to stay with my 15" OZ Alloys.
New set of 205/70R15's Toyo Proxes went on today.
Another item off the list!!

As has already been discussed the rim size cannot be discussed in isolation, the tire size needs to be considered also.

Perhaps more important however is how you plan on using the vehicle, vehicles that are likely to see use on broken or rough surfaces will generally ride better with more rubber between the rim and the road surface, so you would want to consider the smallest rim diameter that will clear the brakes (I think a 15" rim in this case), and the tallest tire you can run after considering the impact on gearing, braking and fouling the bodywork.

You can also go the other way, on a smooth surface, lower profile tires make for better handling, personally a 60 series tires is the lowest profile I'm comfortable with, given the roads in my neck of the woods.