Z4M 245/40/R18 rubbing (18x9 ET30)

[filtercoffee]

Update: Downsizing from 245/40/18 to 245/35/18 solved the issues. Michelin Pilot Sport A/S 3+.

The steering now feels lighter. With the 245/40s it felt really heavy, to the point where it wasn't enjoyable to drive at low speed. Now it's more reasonable, though it still feels heavy and I'd like it to be even lighter. Additionally turn-in feels more responsive. I wonder if these effects are due to the smaller sidewall having less flex, or a change in scrub radius due to the smaller diameter wheel. /shrug. I'm enjoying the car so much more now.

I'm on 18x9 ET30 wheels, struts mounts are pushed all the way in for max negative camber.

My main lesson from this is that seemingly minor wheel/tire changes can make a big difference, and you don't really know until you try it (unless you're an automotive engineer). I guess this applies to all mods really.

[XMetal]

I would not call the steering in the Z4MC heavy. It's not even close to, in terms of "heaviness" when compared to my e53 X5. With that said, I didn't feel that it had made any difference (that I had noticed) when I switched from my stock 225/45/18 to the current 245/35/19 continental extreme DW. Did you change out for an underdrive power steering pump pulley by any chance?

[filtercoffee]

Those two tire sizes are comparable in diameter. (within 0.2") so boosts credibility to the theory that wheel diameter changes can change steering effort.

No steering system mods. My wheels are ET30 though compared to stock ET42.

[tecnicaeleven]

Do you think a 255/35/18 would have solved the problem? Its wider, but also shorter than the 245/40

I ask because I have the same unmounted wheels, and its about time for tires

[filtercoffee]

tecnicaeleven I cannot guarantee.

[lookingforanusp]

So, I'm looking for a consensus. With a properly offset 18x9 with a 255/35 in the front of a Z4M, do we experience rub during high-speed driving? Or only during parking lot (full-lock) maneuvering?

[filtercoffee]

Back on stock suspension

245/35/18 rubs just a smidgeon on the hardest hairpin turns in autocross on the rivets.
9inch ET30.

No rubbing in regular driving or parking lot maneuvers.

[3002 tii]

Originally Posted by filtercoffee

Back on stock suspension

245/35/18 rubs just a smidgeon on the hardest hairpin turns in autocross on the rivets.
9inch ET30.

No rubbing in regular driving or parking lot maneuvers.

What was final camber settings after going back to stock suspension?

[blufc3s]

Originally Posted by filtercoffee

driver side front where the bumper cover meets the fender:

View post on imgur.com

that's where it rubs when I turn right. (well, used to rub)


here's the rub point when I turn left:

View post on imgur.com

michelin pilot a/s 3+. probably should have stuck with 235. oh well. I hope people can learn from my mistake. and any advice is appreciated.

Mine are rubbing in the same spot. The clip that holds the bumper/fender together very near the rub spot is broken. Not sure, but suspect this rubbing may have broken it.
I currently have 225/45/17 tires on 17x7 rims 40mm offset with 20mm spacers. I just ordered 15mm spacers in the hopes this will cure it.

[maupineda]

Use wrong size tires and wheels and be not surprised if rubbing and screwing your liners