Ive never understood ET myself.

only just got to grips with J size.....

i googeled it the other day and had a read but still dont fully get it.
 
Should be fine kn the rear
I am running et 37 with a 20mm spacer ( therefore et 17)
might be a bit closer at the front, but again I have run et 25 on the front with no problems on mine.
Worst comes to the worst get an engineering company to take a bit of metal off the face.

Ollie