Help confused about offsets

[P11CRG]

Hi I'm thinking of a new set of alloys.
Wheels at the moment.

Front 17 inch ET36 7.5j
Rear 17 inch ET 30 8.5j

Replace with 19 inch ET 35 both 8.5j

I need to know they will fit and won't look stupid .

I was wanting to lower the car as well eventually

 

[renault12ts]

What year is your car?

 

[P11CRG]

Hi I'm thinking of a new set of alloys.
Wheels at the moment.

Front 17 inch ET36 7.5j
Rear 17 inch ET 30 8.5j

Replace with 19 inch ET 35 both 8.5j

I need to know they will fit and won't look stupid .

I was wanting to lower the car as well eventually

2006 Plate

 

[hotrodder]

ET works kinda backwards in that for a given wheel width a larger ET moves the wheel inwards i.e. at the rear 19 x 8.5J ET35 will sit 5mm further in than the current wheels.
When you change the width at the same time the picture is altered slightly but there are various ET calculators about which save having to do the maths for example... 1010TIRES.COM - Wheel Offset Calculator which'll tell you that at the front the 19s will stick out 14mm more and reduce clearance to the suspension by 12mm

There's a fitting chart here... Mercedes-Benz Fitting Chart and Wheel Fitment Guide | Alloy Wheels Direct note that for your model all the 8.5J widths have an ET of 28 - 30.

I don't know whether the wheels you're looking at will rub but personally i'd suggest they're too big even if the ET was correct... brakes will look like milk bottle tops through them and a combination of rubber bands for tyres and bigger (typically heavier = more unsprung weight) wheels will lower the ride/handling qualities and probably be far more prone to pothole damage- cracked wheels etc