Rear Tires Rubbing - Corrective Options

[krs]

I'm getting into some territory of topics that I lack the knowledge on.

I'm running the Bilstein B16 Damptronic coil overs on my R, (among other things). These last to autox events I noticed I'm getting some tire rub on the fender lip of the rear wheel wells. For this season I'm on 18x9 ET42 wheels, with 255/35 RT660's. Last year I didn't have the issue with the 18x8.5's. The rear camber is right at -1.9° on both sides.

I'm looking for the best bang for the buck fix on this. I'm really not ready to pull the B16's out, and go down the path of a better coilover/rates setup for autox. I will at the end of their life cycle, but that's not now.

• For those that know, is there a general rear camber setting that is best not to go past? I thought I had read about -2.0° is it. If I bought camber arms and went to -2.5° is this territory that I should stay away from? I'm not savvy on the the rear suspension dynamics to truly know how this is affected.
• I know the B16 DCC spring rates are on the softer side. Is it possible to find a better rate to help mitigate this?

Spring specifications (source Bilstein customer service):

metric (imperial)	Front	Rear
Spring Rate	6.6 kg/mm (371 lb/in)	5.4 kg/mm (303 lb/in)
Top ID	88-90 mm (3.46 - 3.54 in)	61-61.7 mm (2.40 - 2.43 in)
Bottom ID	71-71.6 mm (2.8 - 2.82 in)	55-56.1 mm (2.17 - 2.21 in)
Middle OD	145 mm (5.71 in)	121 mm (4.76 in)
Wire Diameter	13.25 mm (0.52 in)	13 mm (0.51 in)
Overall Length	215 mm (8.46 in)	215 mm (8.45 in)

• Size down on tires? These tires are pretty new, with only maybe 20 runs on them. I hate to ditch them so early in their cycle.
• Raise the car up? I'm not sure at what height I'd need to go to prevent the rubbing under compression.

I don't feel the car is really that low, but I guess I could try that and see.

Any thoughts?

 

[tigeo]

660s run big. Go down to a 245/35.

 

[krs]

I ran 255’s on my 18x8.5 wheels though, guess the small change in offset pushed it closer.

RT660's aren't made in a 245/35 so I would need to go to a 40, and probably be right back where I'm at?

Okay so a $1,200 fix.

But to the camber question… if I add -0.6° more camber, wouldn’t that effectively move the top of the wheel in approximately 3mm under compression?

 

[ChristopherNeil]

I would start with adjusting the camber in a little and correcting the toe. Cost of 2-wheel alignment is going to be minimal, but at least you'll know. Or, you can run a 235/40 in the rear. The contact patch on that model tire is like a 245+ in other brands anyway.

 

[xXDavidCXx]

I would start with adjusting the camber in a little and correcting the toe. Cost of 2-wheel alignment is going to be minimal, but at least you'll know. Or, you can run a 235/40 in the rear. The contact patch on that model tire is like a 245+ in other brands anyway.

And if you can't get what you need from the alignment, raise the car up.

 

[Treadup]

Just a word of caution. Check your right rear inner wheel clearance. I had -1.9 or so camber for a minute when I went to 18x9 with 245 tires and I was rubbing on the guard for the fuel filler neck and fender liner.
I went to a shop that said “that’s what we do is deal with lowered cars” for the alignment. They charged me full price to reverse what they did as well. Anyway

 

[krs]

Just a word of caution. Check your right rear inner wheel clearance. I had -1.9 or so camber for a minute when I went to 18x9 with 245 tires and I was rubbing on the guard for the fuel filler neck and fender liner.
I went to a shop that said “that’s what we do is deal with lowered cars” for the alignment. They charged me full price to reverse what they did as well. Anyway

View attachment 300060

Yeah, I don't think that's as close on the R, but I have zero rubbing there. Only on the lip of the fender.

 

[xXDavidCXx]

Yeah, I don't think that's as close on the R, but I have zero rubbing there. Only on the lip of the fender.

Correct, this is a GTI only issue.

I solved it by cutting back the liner and moving the tank to clearance the filler neck.

 

[2LEEGIT]

Non-DCC B16 comes with F7.1/R7.4 spring rates and I’m running -1.5deg.

 

[Jmitchell4873]

Correct, this is a GTI only issue.

I solved it by cutting back the liner and moving the tank to clearance the filler neck.

Sliding the tank allowed you to butt the filler neck all the way up to the "frame" rail? Or did you do something additional to gain clearance?

I haven't driven on my 245/45/17 RT660's yet, but I am currently looking for options to keep those tires instead of asking Discount tire to swap them out.

 

[krs]

Non-DCC B16 comes with F7.1/R7.4 spring rates and I’m running -1.5deg.

My SPC camber arms should be here this week. I'll get them put on, with a new alignment Thursday. It's a back to back Pro-Solo weekend, ideally I'd like to get it all done in between so I could see if the changes mattered. Well, matter aside from "hopefully" not rubbing anymore.

 

[xXDavidCXx]

My SPC camber arms should be here this week. I'll get them put on, with a new alignment Thursday. It's a back to back Pro-Solo weekend, ideally I'd like to get it all done in between so I could see if the changes mattered. Well, matter aside from "hopefully" not rubbing anymore.

How will camber arms help? Are you running the minimum camber already? More negative camber will not help this problem.

 

[xXDavidCXx]

Sliding the tank allowed you to butt the filler neck all the way up to the "frame" rail? Or did you do something additional to gain clearance?

I haven't driven on my 245/45/17 RT660's yet, but I am currently looking for options to keep those tires instead of asking Discount tire to swap them out.

Sliding the tank over plus I used a plastic plumber strap to hold the filler neck to the body.

 

[2LEEGIT]

How will camber arms help? Are you running the minimum camber already? More negative camber will not help this problem.

They will bring the top of the tire in and increase camber, thinking the route KRS is going. KRS is not having issues rubbing fuel filler’s neck like our GTI’s.

 

[Jmitchell4873]

Sliding the tank over plus I used a plastic plumber strap to hold the filler neck to the body.

Hell of an idea there! I will definitely see if I can get the filler pushed in a little tighter.

Mine seems to have a slight bulge that pushes right into the path of the tire. Thanks for the info!