19mm less clearance from the strut is not a lot if you're using stock suspension. You should be able to assess that by sticking your hand inside the guard checking the clearance.
Ideal offsets would be around 18x8 +30 / 18x8.5 +35 fronts and 18x9/9.5 +35 - +40
The above offsets are just a guide and are very conservative to fit stock guards without any rolling or lipping and will most likely keep the wheels either flush or within the guards (legal).
The fronts are tricky as you will also need to find a wheel which clears your front brakes (4 pot). To be safe I always test fit the fronts or ensure they have high disk clearance.
Rule of thumb, if the fronts have massive dish and the spokes are flat, then it probably won't clear ur brakes.
And don't let wheel shops tell u its OK to fit spacers to make them clear coz they are illegal.
Post up the type and make of wheel and their specs if you have them.