Vx 15'' tyres

[1107187]

My recently purchased VX Accliam has 235/45 ZR17 97W tyres fitted and I'd have to say after a trip from Emerald Qld to Brisbane and return on the rough stuff its rougher than rough but on the motorways its lovely so I'd like to replace the 17'' with 15'' tyres and Cragar S/S mags.
I'd say 80% of the driving time will be spent on the country roads so I need higher tyres to asborb the shock of the Queenslands roads.
The 17'' tyres are 235 so I'm wondering if the 235's in 15'' will fit without any issues or what other 15'' tyre sizes do others have fitted to the 2000's Commodores.