I currently have 19x9 wheels with a +32 offset on my 2009 G37X Sedan for my winter wheels with 245/40/19 snow tires on it. I want to lower the car with coil overs later this year... When I look down the wheel from the top of the wheel arch, the rim sits slightly farther out than the wheel arch, which I feel might cause tire rubbing if I lower the car too far.

I want to get another set of wheels to put summer tires on and I've found some 19x8.5" rims that I like. I can get them as a+35 or a +43 offset. Which offset will move it in more than my current setup and allow me to drop the car down 1.5 to 2 "? Also, can I go with a 255 tire on the 8.5" rims?

this is the current setup.

 

The tops of the wheels will pull inboard as you lower the car.

1.5-2" is a huge drop for that car...so you'll need some additional alignment parts and all that. You can just use those to ensure wheel clearance with the fender as well.

To answer your questions...

A higher offset will pull the centerline inboard.
A lower offset will push it outboard.

Offset is just a centerline measurement, however.

Imagine looking at the wheel either directly from the front or back of the car. Then imagine grabbing the centerline of the wheel and dragging it inboard/outboard.

Where the wheel face ends up will depend on width and offset combined.

Plenty of illustations of this available via a youtube and google search to help your understanding of it.

The reason I'm typing all this is because there's no direct answer to the perfect fitment for your car...especially since you'll be using an adjustable height system, as well as (presumably) alignment adjustments to make everything work.

Alternatively, you can look at pics of other peoples' setups and ask them how they achieved it.

My recommendation for driving feel is to stick to an offset around +45. A width of 9" will work well with that offset, to clear fenders easily, even if you use close-to-stock alignment angles. Use a 245/45/19 tyre.

A 9.5 +45 will fit well if you can live with a bit of camber. Use a 275/40/19 tyre.


There's no good way to use an 8.5" rim, IMO. Either the looks will be compromised by using the correct offset. Or the function will be compromised by using a too-low offset.


If you're dead set on using 8.5, then you'll want an offset around +35 for the sake of looks. Both will work fine with your fenders. The +43 option will work better for driving feel, tyre wear, and component life. BUT...will look extremely weak. I wouldn't go beyond a 245/45/19 tyre with an 8.5" wheel.

 

Hugh, thanks for the very detailed reply, I'll do some looking around.