Fitted some 265/35/19's on the front. Looks like I have about 2mm clearance between tire and the upper ball joint crown nut. Need opinions, is this safe?

 

Looks dangerous to me.

 

Not really vibing the rub marks on the upright either.

 

Did you measure clearance between sidewall and upright as well? Clearance of 2mm to the crown nut does not sound good, but I am trying to figure out why 265/35-19 is so close when it is only ~0.2in larger OD than OEM size, depending on the tire. What is the wheel offset?

I think I checked and found a finger-thick gap to the crown nut on my 275/35 18in square setup, but after checking my notes I did not write it down. I am doing a service soon and will post what I learn.
https://cimg5.ibsrv.net/gimg/www.clu...56dd5dc86a.jpg

 

I suspect what looks like a rub mark on the upright is just accumulation of dirt and grime in that spot. Here's another angle, looks like decent clearance there, though I did not measure yet.


You're right, I should measure clearance to the upright for due diligence, though I don't think theres an issue there. My wheel is 9" ET+45. Makes sense actually that you had finger clearance to the crown nut with a 275/35/18 as it's only 25.6" diameter vs my 26.3". I thought I previously saw others on here running 265/35/19 on the front with no major issues so I went for it. I cringe at the thought of only 2 or 3mm clearance but in theory that distance should never change since the knuckle is fixed to the wheel. I was hoping someone can confirm that for me so I'm not paranoid about it. Done a couple hundred km on the highway and so far no indication of interference. I will definitely need to modify the plastic liners though as it scrapes on tight turns and dips.

 

The tire moves under load. Looking at it statically tells only a small piece of the story. Your other pic does nothing to dissuade me from the wipe marks on the upright. I have those with a 255/35/19 and a +45 offset on an 8 1/2" wheel, so I know under load the tire is deflecting and rubbing on the upright. The only way to see this is with a camera under load. You'll never see it unloaded.

Why did you choose this size? If you are expecting a mechanical grip improvement, I'd say you're optimistic at best. The tire size changes everything the suspension engineers put in place for the car to perform by increasing the diameter pretty significantly. Scrub radius is off. Instant centers are off. Roll couple is off. Roll axis is off. If you haven't modeled this, you really don't know what you're getting and more than likely it's not an improvement.

 

I'll have a closer look at the upright when I take the wheel off but I'd be surprised if the tire is deflecting laterally at the top of the tire. At and near the contact patch yes, but not up top. I suppose the tire could "grow" from centripetal force at high speed and that would be concerning wrt the crown nut clearance.

The reason I chose this tire (continental extreme contact force) is because it's the best size combo option for my wheels from available 200 TW tires. I agree the larger diameter will affect suspension and steering geometry but IMO not by any appreciable amount. The radius is only 0.1" larger than OEM, a difference of 0.7% and is less than half the typical tread depth of a typical new tire. Ultimately, if I keep these, I'll see how it affects lap time next time I hit the track.

 

I see the same rub marks on my car with Michelin PS4S in a 255/35/19 on an 8 1/2" rim with a +45 offset. I disagree that the tire doesn't deflect at the top. Physics disagrees with this assessment. If the bottom moves one way, the top will move in the opposite direction. It's fundamental to how pneumatic tires work.

 

Finally had time to catch up with maintenance two weekends ago. Findings:
1) I measured a 9/16in gap between the crown nut and tire. Tread depth currently ~7/32nd's.

9/16in clearance between crown nut and tire.

2) Front uprights were so dirty from road grime that I could not discern any rub marks on them. However, I did notice some weird marks on the inner sidewall of the then-rear tires, which had been on the front when new (before first rotation). No similar marks on then-front tires. Evidence of rubbing during aggressive canyon driving when new? Not sure, but the area looks about right for the close clearance to the front upright.

Evidence of rubbing on inner sidewall?

If there was rubbing, I had expected to see the hatched lettering "sanded" down, but that is not what happened. I also expected to feel it as feedback in the steering wheel, and in those weekly 7/10's canyon runs I never did. The outside front is the most loaded corner and I am thinking a rub should feel like understeer(?)

3) The best way I could think of to get definitive evidence was to use a white paint pen on the front upright to make a "witness sample". Looks ugly, but hopefully will help clarify the situation going forward.

Used a white paint pen normally for marking suspension bolts to scribble a "witness sample" on front uprights.

4) Found a major rub on left front fender liner. I had heard a scrape on a deceptive freeway bump and wondered what it was. Mystery solved.

Ugly burn-through on LF rear part of fender liner. Likely 105 East near Long Beach Blvd, fast lane.

There are many variables between tire models and use cases, but for now I would recommend caution for those considering 275/35-18 square setups on a lowered ISF. Interested to hear reactions from other square setup folks. @lexicon72 @Jwconeil

 

Do you see similar marks on the outside sidewall? Looks to me like pavement rubbing due to the sidewall folding over in corners. These DWS have terribly soft sidewalls.

 

I agree that it looks like outside pavement rubbing. Only time I have ever rubbed was one particular corner at Mid Ohio and it was the outside part of the fender liner. But I don't rub on street or other tracks.

 

No similar swirl marks on outer sidewall. I doubt the swirls are pavement rubbing...the inner shoulder blocks are not even worn to the edge, see raised "TWI" lettering at left side of enlarged photo below.

Another possibility might be mold release residue...inner sidewall were never washed. Witness stripes on upright should unlock the mystery at next tire rotation. I will clean them next time before inspection, coating of brake dust makes forensics difficult.

I agree, DWS sidewalls are much softer than Michelin's I am accustomed to.


Inner shoulder block, marked up to show edge of wear pattern.


Another photo of weird inner sidewall swirl pattern.