The gt 147 and 156 share the same underpinnings. A space saver, tool kit and jack from any of them will work on any one of the others. Although most 156's use 19mm wheel bolts where the 147 and gt use 17mm bolts so the spanner will be the wrong size.
The rolling radius of the 18" gt wheels is the virtually the same as the 17", 16" & 15" wheels fitted to the aforementioned models. There is a very slight difference on account of the different tyre sizes but for the purpose of this thread they should be considered to be the same.
The only issue with using a spacer save on a gt (and gtas) is that they won't clear the brakes fitted to the 3.2 gt. So if you get a puncture on the front, you have to swap the rear wheel on to it and use the space saver on the back. Fortunately you can jack both wheels up using the supplied jack so it's just a question of time.
I would also note that if you use the factory supplied goo to repair a puncture at the roadside you have to replace the tyre. Not ideal given how much the 18" tyres cost.
As a final note, I have come across a space saver that will clear the smaller 305mm brembos fitted to the gta's (not the gt's). I think it may have been off a gta or possibly a gtv v6.
Last edited by Chris155; 08-06-11 at 14:14.