The existing rims are 16" but were not in good condition. As far as fitting is concerned, there is no issue of width provided you go for wider rims. But in terms of handling and fuel consumption, a daily runner suzuki should not have wider tyres than 7". In my personal opinion, 235 75 R 15 is the best size for a 1300cc both for tough offroading and daily running. Also it doesn't effect the suspension. So if you are planning to change the rims, go for 15" rims and tyres. In rigid vehicles (as of a suzuki), a smaller rim with bigger tyre combination is always the best combination as in case of offroading on bumpy roads, one can always reduce the tyre pressure and gets a better ride.
If i am nor wrong, you did purchase 15" alloys for the veh?
Regards
Noman