275s and Sluggish Steering

B8 S4
#1

I recently installed some 275/35/19 PSS ON 19x9.5 ET45 wheels. They were installed at the same time as Bilstein PSS10, adj UCAs, cornerbalance, and alignment. FTG is 26" (+/- due to cornerbalance). We started with:
Camber: -2.3F / -1.8R
Toe: 0F / .05" total toe-in R
Caster: 4.5deg

After driving this setup, the steering was slow to return to center. I asked to max out caster to see if it could fix the issue. We ended up with the following:
Camber: -2.3F / -1.8R
Toe: .07deg total F / .12deg total R (I don’t know why the second sheet switched from inches to degs)
Caster: 6deg

This helped, but it’s still slow to return to center. It returns to about 1/8 turn from center, but won’t return without me correcting it. Is this due to the 275s impacting the scrub radius? Is it because of the minimal toe? I was informed we couldn’t get any more caster. Do you have any ideas what we can try, while still keeping the wide tires, or do I just need to live with it? Preferably, I’d like it to snap back to center.

Thanks in advance!

#2

Well that is a decent amount of tire all around

#3

Do you think it’s the tire width alone that could cause this issue? Around sweeping turns on the throttle, I can let go of the wheel, and it will hold the line around the turn. Is this a symptom of low/zero toe-in?

#4

Let go of the wheel on sweeping turn and holds its line? Really?

Seems odd to me. I have 265/40 with similar align specs, even less toe. As close to zero as can be. 2.3 camber up front and 1.7 camber rear with 4.8 caster. I would never think of being able to hold line on sweeping turn without hands on the wheel

#5

275 is a big tire to have on the car. even with the size if you had the suspension sorted out it shouldnt be that off on comming back to center.

Are there any differences in the cars ability to come back to center basied off speed.

Also what tire pressure do you have them set at.

#6

Yes - on wide, sweeping turns (wheel turned 1/8 turn) on throttle, it will hold its line. It’s like the returnability is dead between 10 and 2 o’clock. On sharp turns, the wheel will return, but slow as it gets closer to center, and stop at not-quite-center. I wonder what could cause this.

#7

It doesn’t appear to be too dependent on speed, but it is somewhat dependent on throttle. Holding steady throttle around a sweeper = steering holding its line stronger. Tire pressure is 40psi all around.

#8

I dont think the low toe is causing it. From what I know, toe in specs are usually much more than zero and even the amount you have is likely not within factory spec. I run less and found even on low end of spec still wear tires quickly so I set mine at 0. Toe in helps hold car steady straight line and less toe can feel like the car is dancing and slightly less stable on hwy straight lines.

#9

it’s scrub from the uber wide front tires.
you’ll also find less steering feel (feels more dead - not as much feedback as previous) and reduced steering response. It’s a tradeoff one makes for greater ultimate grip on the front axle.

Toe isn’t going to fix it.

#10

Yeah the s4 I drove had 265 or 275 and rubbed as well pros and cons. Possibly do a 265 or 255 that is super grippy?

#11

I have long resisted the 265/275.

#12

Thanks for chiming in. I was afraid that was the case. I truly enjoy the grip and look of the 275’s, but the impact on responsiveness isn’t worth it. After these wear out, I’m going back to 255s.

#13

Yeah lighter and that’s plenty of grip on the s4 IMO

#14

275/30/19 would have been a better option. 275/35/19s are not only wider, heavier, but they are also TALLER. Most likely the reason you’re getting the sluggish steering symptoms