My GPS has 17 inch wheels with 205/45/17 tyres and a standard steel GP wheel which is 15 inch and with a 175/65/15 tyre has a very similar circumference, does anyone use this for a spare,would it be safe ?
Im only talking about an emergency get you home option and would guess it would be better on the rear of the car.
Only considering this as a 17 inch wheel seems bloody hard to get hold of.

You've just asked the same question that I was going to ask... Almost! I'm looking to get rid of the 'repair kit' and get a steel spare.
Wait for some answers!

There's a guide on how to put a 5th alloy wheel in the space of that kit. Maybe that could help?