I know this subject has been beaten to death on this forum and I've searched all over this forum but I can't find an answer.

Most people seem to be running 25mm-33mm offset. Hartmann's website guarantees fitament but I'm a little skeptical. I looked in the front wheel well and the space between the steering arm(?) and the tire is very tight. I have 18s on them now.

Anyone using 20x9 w/40mm offset rims? I'll be going with the recommended tire size, 255/45-20. Any help would be greatly appreciated.

 

Achtuning shows how the +40 offset sits on the Q5. Personally it looks a little weak and not as muscular as the 35 or 25mm offsets.

http://achtuning.com/new-products/ar...h-your-dealer/

 

Assuming your wheels on now are 18x8 ET39 standard wheels (8R0 601 025 C) then putting on 20 x 9 ET40 means that the 20" wheels will go 14mm closer to the strut...on your observation that there isn't much gap that would raise doubts but the pics on the link foobs posted shows otherwise.

 

I have also been looking at replacing my current 17x8 OEM wheels (ET40) with 20" wheels. I have done a rough measurement between my current wheel and the suspension arm at the front and the gap is around 20mm, so fitting a 9" wide wheel with a 40mm offset will leave a gap of around 7mm. While it fits, personally that's a bit too close for comfort. Ideally you'd need an offset of 28mm or less to keep the same clearance. I'd recommend to go for 25mm offset if you don't mind the tyres to stick out an extra inch, or go for the ET33/35 wheels if you prefer a less aggressive look.

 

Thank you ya'll.

I just had my Hartmann 20x9 rims w/40mm offset mounted today with 255/45-20s. They fit perfectly! The new wheels stick out approximately 1/4" more than the stock 18x8 w/39mm offset wheels. The 25mm offset rims would stick out an additional 1/2" (3/4" total). I prefer this over the 25mm, though the additional 1/2" may make the tires look more aggressive.
I was mainly concerned about the space between the tire and the control arm (front wheel well) but it was not an issue; I wanted to stay away from using spacers-just a persoanl preference. With the stock 18x8 rims, there's about 0.75" of space between the tire and the control arm (the narrowest area between the control arm and the tire, along the control arm). You can get a feel of this tight space by running your finger between the control arm and the tire. With the 40mm offset rims (20x9 with 255/45-20 tires) this distance is reduced only by approximately 0.3" still leaving around 0.45" of space. NO SPACERS required!

 

Which model did you go with? Post up some pics.

-tgt

 

I've spent some time doing the math on this "offset" issue so I'll throw in my .02.

The key point you are missing here is that the tightest gap between the control arm and the tire is where the tire curves (area between the sidewall and the tread). If you measure that angle, it's approximately 45 degrees; this 45 degrees is very important to know and I'll explain why later. With the stock set up (18x8 with 39mm offset rims), the "backspace" is 154mm-check out http://www.rimsntires.com/specs.jsp. Using a 20x9 with 40mm offset rims, the "backspace" is 168mm. This pushes the rim/tire 14mm into the wheel well. Okay, the 45 degree importance... Since the tighest area between the tire and the control arm is located on the curvature of the tire (the 45 degrees), we can solve this distance using simple geometry. Since the new rim/tire moves in an additonal 14mm horizontally, the gap between the tire and the control arm (the 45 degrees area) will decrease by only 7mm. Since the tighest distance between the tire and the control arm is about .75"/19.05mm (probably a little more), you will still have 12.05mm of space with the 20x9 40mmm offset.
I used the caveman method of measurement by sliding my index finger between the control arm and the tire, before and after the installation. You know what.... I was right! That 7mm is bearly noticeable. You can trust Harmann wheels when they say that they gurantee fitment. Enjoy!

 

I failed Photography 101 but here it goes!

 

^Those look great!

 

Thanks! If I were 10 years younger and had cash pouring out of my pockets, I'd lower it like yours. That's a sharp looking ride!