Hey guys. I'm thinking of putting 20mm spacers on rear wheels and 12mm on front. If you've installed spacers and have some photos, I'd really appreciate it. I have 19 x 8.5 wheels with 38 offset. Think the 12/20 set up would look pretty aggressive but not over the top. Opinions welcome...

thanks

 

Don't have pics but I use same 12/20 spacers in my case with 20 x 9 OEM wheels at ET 46. Your offset sounds a bit non-stock though (I thought the OEM 8.5's were in the mid 40mm range, at least the baseline 18"'ers. When I checked my 18" OEM C5 RS6 wheels for fit (also 8.5" width), they were somewhat out toward fenders relative to my OEM 20's. ET on those is 30mm. Thus, you might need to cut back just a bit. On mine, 25mm in rear is aggressive as an example; tried it. Works, but pretty pushed out. Might rub a tiny bit in theory, though I didn't observe it ever over 1,000 miles of trying it. Ditto on slightly too aggressive with 15mm on front vs. 12mm; didn't see any rubbing there BTW. But, if you cut back to less than 12mm in front you can't get hubcentric, at least in H&R.

To be sure of where you will end up, my net is 12 front 20 rear is about maximum totally rub free and no question about appearance at 9" rim width and ET46 with 275/35-20's. Using those numbers and your ET and width, you can back into the equivalent spacer with your width and ET.

 

You may like this site:

http://www.rimsntires.com/specs.jsp?...&text1=&text2=

 

It doesn't directly tell you the comparison to get to how the tire will look relative to the fender opening. But, subtracting the wheel width from the calculated backspace, I get the same 2.2" for my 20" wheels and the ET 38 8.5" wheels from the OP. Thus, those wheels seem to be out closer than the baseline 18" A8 5 spoke wheels in 8.5" width (which in turn are pretty tucked into the fender wells. Those OEM wheels I still recall have an offset in the 40's. Meanwhile, the inference from this calc. would seem to be with the 12/20 spacers from the first post, it would net to what I have appearance wise as well as (non) rub wise relative to the fender edges. In turn that appearance is just right to me--meaty, pushed out toward fenders, but everything fits just right.

Calculator makes several interesting assumptions too, like the 255 wheels (either ty 18's or 19's in the 45 and 40 profiles) on A8's yield accurate speedo's. Since those are known as pretty off (like 5MPH around 60), the 275's (also a factory OEM size) actually clean that up in part. Weights vary a lot with wheel selection (like 5 pounds in 20's just based on "old" vs. "new" RS4 style, or the lighter 19" (forged) OEM pieplates compared to the heavier 18" cast OEM five spokes) and by tire type too. Still, assuming they have the math right, a lot easier than doing relative (to fender edge) appearance calculations like these on a calculator each time.

Thanks!

 

Thank you both. My wheels are not stock. They are Hartmann reps. They fall in same place as stock 19x9 44 offset because of wheel width difference. Therefore 20mm spacers should be ok but I hear you. Might try 15mm in rear and 12mm front, or just 12mm rear and nothing in front. I'm aware of the hubcentric issue so wont go below 12mm.

 

If you check the link you can see that your wheels are 2 mm further from fenders. According to that you can follow his setting with no problem.

On the other hand, that would bring your front wheels 20 (19) mm out compared to the stock and that is serious change of steering geometry that can cause torque steering. That implies that Audi engineers new what they were doing at the first place designing it.

 

my wheels are out 12 mm from "stock" (i.e. the spacer) since my 20's are OEM W12 sizing and ET (and S8). And no evident torque steer effects (as in, zero) at 450HP and W12 torque levels.

Look at C5 for comparables on where Audi goes OEM on variabilty in overall wheel placement and net offset geometry--when you compare the base A6 to what they eventually came to in the 4.2 A6 and then the RS6, they moved the front wheels outboard so much that of course they flared the fenders. And it was all done via the wheels and relevant ET's and widths. Actually on the allroad they ended up at an ET of only 20 mm on not particularly wide wheels (which counteracts the ET mathematically at half the rate of change). RS4 on 19 x 9's w/ lower ET's vs. skinny tired, inset wheel baseline A4's might be another, although C5 4.2 and allroad flares let them move the wheels around a lot more on that chassis.

Meanwhile on the rear of the D3 I expect moving the wheels out on a relative basis to the front (i.e. no front spacers, or smaller ones) would reduce classic understeer dialed into most Audis, if desired.

 

It’s good to know that 12 mm spacers doesn’t cause any torque steer. Not sure about 20 mm. Regarding other models I am not so sure that steering geometry is same for all of them. Small variations in attaching points and arm lengths make big difference.

Regarding under steer I think it is just the opposite. In order to reduce under steer you have to improve front grip or reduce rear one. Making rear track wider increase rear grip. Using wider tires with more grip on front wheels might do the trick but it would look pretty ugly.

 

Have used both 20 mm and 25 mm in rear of car. Then later the 15's and then settling on 12's in front. Only issues at 25 mm in H&R DRA's have to do with machining of "new" vs. "old" style RS4 wheels for the 20" Audi OEM D3 fitments, and separately theoretical minor rub potential in upper rear fender lining at extreme compression I only found with a floor jack carrying full weight of wheel corner and more. I covered several years ago now in posts in archives. Translating that across wheel widths and ET's was the earlier theme of the thread.

As a longtime board poster/user, if you go back into archives history, others have used 25's (usually with the 8.5", mid 40's offsets in OEM A8 wheels). Another issue still not tied off from original post--OEM 8.5's for D3's are typically in the 40's ET, not in the 30's as far as I know. That delta from 8.5 to 9" widths but where both OEM offsets are in the 40's is underneath why I think some report using bigger spacers successfully--the actual wheel (tire) position to the fender varies depending on which OEM wheel and width it is. Meanwhile, a few posters went to 30mm spacers in rear even, with presumably OEM wheels and I expect in the 8.5's and mid 40's ET. In another set of threads, CovertW12 (who is now back to an RS6) pushed right to the edge of offsets and tire sizing, using mostly 9" wheels but maybe some 9.5's [would need to recheck archives]; he seemed to have the most experience among posters of exploring the limits of offsets, wheel and tire sizing.

There is no steering effect I can perceive in the field. Marginally might improve stick and tracking for a given set of tires and wheels, but on 275 PS2 summers and S8 level roll bars its pretty much beyond anything to find limits of on the street. From practical/field experience on a 450HP, much higher torque car than the 4.2's. Covert W12 even at 285 CS 3's and various other fitments (on a W12) never reported negatives (rather, positives) in all his offset and wheel width experiences that I recall.

 

For me upsetting the balance of suspension geometry is too high price to pay for a minor change in appearance. I would never advise that moving the centre of the contact patch outside the virtual kingpin axis is a good idea, however wide the tyres and small the offset it is still bound to adversely effect steering feel and stability under acceleration.

As for the rear, I think it is likely to cause little problem but it will put added load on the suspension strut.