I Imagine the offset is in the centre but its only 3 mm difference front to rear but the width will be in the rim.
You could re calculate the front and rear offests with the new figures
a stock front is 7.5j 41 offset
the new would be 8.5j 47 offset
if both wheels where 18's the result would be
Compared to your existing wheel, this new wheel will have an inner rim which is 18.7mm closer to the suspension strut. The outer rim will poke out 6.7mm more than before.
I think you would be ok with what sticks out but not sure you would get your inner clearance.
Swapping front to back will mean the rear tyre can not be 255 as the rim would be too narrow to carry it.
I think you could run themon a 1.9 anyway the fronts need to be spaced the back may fill the arch with out again you could work that out but you need the wheel sizes you have fitted and then its possible
You could re calculate the front and rear offests with the new figures
a stock front is 7.5j 41 offset
the new would be 8.5j 47 offset
if both wheels where 18's the result would be
Compared to your existing wheel, this new wheel will have an inner rim which is 18.7mm closer to the suspension strut. The outer rim will poke out 6.7mm more than before.
I think you would be ok with what sticks out but not sure you would get your inner clearance.
Swapping front to back will mean the rear tyre can not be 255 as the rim would be too narrow to carry it.
I think you could run themon a 1.9 anyway the fronts need to be spaced the back may fill the arch with out again you could work that out but you need the wheel sizes you have fitted and then its possible