i just got Swift springs installed on my 2017 IS350 F Sport, now the 18'' F Sport wheels look tiny and tucked in. what are the offsets on the F Sport 18''? here comes a newbie question, the small the offset the wider the wheels is this correct? for example +25 is wider than +45? what would be the recommended width and offset for my car right now after just lowed by Swift springs for about an inch? i prefer stick with the 18'' wheels.

 

Offset specs:
Front: 18X8 +40 offset
Rear: 18X8.5 +50 offset

The offset refers to the distance between the true centerline of the rim and the hub mounting surface of the rim.
The smaller the offset (as it pertains to the IS), the more the body of the rim is pushed to the outside of the vehicle, as the hub mounting surface is pushed to the back of the rim.
The offset will be determined by the width of the rims you purchase. Example...Front 8.5" wide and rear 9.5" wide, you'd be looking at a rim around +32 to +35 in the front and +35 to +40 in the rear.
That's just a rough guideline as rim design plays a factor as well.
If you want to push out the OEM rims, consider a 25mm spacer for the front and a 20mm for the rear. That will give you that flush look without breaking the budget.

 

thanks, that was exactly what i was looking for.