Strange but surprisingly satisfying configurations

[Nkc]

So for the longest time that I've had the Z4, I had it on ESS stage 2 tune with wide 20's on it and running Sport+ and S for the DCT. Lately, I've been tinkering with the limited amount of resources I have and came up with what I think feels amazing for our car.

1) Double staggered wheels
19' 225 in the fronts
20' 295 in the rears

2) Tune back to ESS stage 1. Stock mode was just ridiculous after running stage 2 for so long.

3) Sport mode with M/shifts.

I feel the balance and grip to be much better than what I've experienced with for so long on this car. On ESS stg 2, I can't seem to be able to put the power down consistently and the power is choppy. Stg 1 power is a lot more progressive and has a more NA feel to it. For the wheels/tires setup, the car was a lot more lively with the 19's and extremely planted on 20's but neither options felt right (Story of the 3 bears kind of deal). For whatever reason I still can't quite explain, the 19's with 225 in the front and 20's with 295s in the rear gave the car a perfect balance, especially thru mid cornering and weight transfer.

I do kind of look stupid with 2 different looking sets of wheels for the front and rear tho.

You guys experience any other setups?

[rking117]

i must see your wheel setup. it must really look different.

[nicknaz]

I went from stock width 19s to stock with 18s to +10mm wider 18s and I like the 235/265 18s setup a lot

What were your original sizes?

Do you think your sizes were so off (ie. diameter difference of front vs rear) the electronics were freaking out thinking you were having traction issues in corners and cutting power unnecessarily?

[Nkc]

Original sizes were
225/35/19F and 255/30/19R
and
245/30/20F and 295/25/20R

Now I've combined for 225/35/19F and 295/25/20R

I'll post pics of this funky setup later.

[Gunzaro]

My Lotus uses 16inch front and 17inch rear from factory but that's to reduce front end grip. Interesting results for the e89. What suspension do you have - the stock sport suspension would be tuned for 19's all round.

[Nkc]

Eibach springs and h&r sway bars.

[Asbjorn]

Originally Posted by Gunzaro

My Lotus uses 16inch front and 17inch rear from factory but that's to reduce front end grip. Interesting results for the e89. What suspension do you have - the stock sport suspension would be tuned for 19's all round.

Actually when running oem RFTs the 19inch equipped Z4s slaloms/corners slower than those with 18inch. But that is probably not the suspensions fault. With better tires or when switching to nonRFTs the results may change.

Anyway, take a look at the tire sidewall height on racing cars, dragsters etc. Even the Boxter uses taller sidewalls than the Z4. It is a trade off between looks and grip/comfort etc.