Trying to fit some 18x9 255/35/18 wheels in the front

[hc1001]

I wanted to go 18x9 all around for the track this year. Is anyone running something similar and could provide any help?

I had to change up my suspension setup to raise the spring perch high enough to clear the tire and also go from 12mm to 15mm spacers to clear the rim from the strut housing. Im on KW V3 struts with 60mm 500lb springs, 15mm spring spacer(to fill in the droop gap), vorshlag plates with -3 camber and most positive caster setting. I have only changed the driverside to this new setup currently and tested it on the streets for 20 mins. Didnt have any problems but the track is very different than street...

Should i decrease the caster to pull the wheel back a little from the front bumper to get some clearance in case it compresses enough to make contact with the fender/nosepanel/bumper? If i dont have to, id like to keep the advantages of more positive caster. I was also looking into Hard motorsport front bumper canards to keep air from directly hitting the tires, has anyone done this and provide a before and after experience? If it doesnt make much difference, i can skip them.

I would like to avoid smashing up my front fenders. Any help would be appreciated. Thanks.

[Team Neverlift]

You don't mention what your caster is set at, just that it is maxed out. Definitely need hard numbers to see where you are at....

Anyhow, I have been running 18x9.5 +35 w/ 12mm spacer on Bilsteins & springs at the track for the last couple of events... -3.5 camber, 6.5 caster (was on 17s for a year+)

Yesterday, I had KW v3 w/ Vorshlag plates that were installed over the weekend aligned, still running 12mm spacer (could run more negative camber w/ more spacer), -3.5 camber, 6.4 caster. I also run 245/35 RSRR currently.

[hc1001]

Hi, Thanks for replying.

Im using the default caster setting on the vorshlag plates(max caster). The vorshlag default caster setting is also suppose to replicate the stock 96+ E36 M3 caster setting so it should be around 7.6-8. I do my own alignments so i never check caster since its set to max caster on the plates.

Do you have any pics of your front wheels? Im assuming your alignment #s are for the E36 328i in your profile? I would think you would have more caster since the 3 series strut mounts are centered and the vorshlag is more towards the rear of the car at default caster setting.

Thanks.

[Team Neverlift]

Hi, Thanks for replying.

Im using the default caster setting on the vorshlag plates(max caster). The vorshlag default caster setting is also suppose to replicate the stock 96+ E36 M3 caster setting so it should be around 7.6-8. I do my own alignments so i never check caster since its set to max caster on the plates.

Do you have any pics of your front wheels? Im assuming your alignment #s are for the E36 328i in your profile? I would think you would have more caster since the 3 series strut mounts are centered and the vorshlag is more towards the rear of the car at default caster setting.

Thanks.

Was running flipped E36 M3 96+ top mounts w/ 95 M3 offset bushings... caster was 6.5. With the Vorshlag plates, I would need adjustable lollipops to exceed +6.5 caster.

This pic is from the Bilstein / H&R race setup.... I will try to get a better pic of the current wheel inclination w/ the Vorshlag plates this evening.... but it should appear identical.

[hc1001]

Thanks for the pic. No need for additional. Yea that makes sense if u were on 96+ m3 strut mounts and went to vorshlag. It would be similar caster #s.

So, do you have any issues with tire rubbing on the track? That setup looks lower than my setup. What conditions cause the rubbing if any... hard braking, uphill or downhill long sweepers? I just want to sort this out before the track and not while at the track.

Thanks,

[Team Neverlift]

No rubbing really. There is one exception, but it is hard to explain the circumstances that cause it, as it only happens at 1 track, in 1 spot, and under 1 condition... it is hardly noticeable at all... I will just occasionally remove slight rubber build up from the inside edge of the passenger fender when visiting this track.

Before I went down to the 12mm, from 15mm spacers previously, it would rub more often on both sides, while under front weight transfer that included some steering input.

I should also mention that when I installed the Motion Motorsports undertray, I noticed my tires were occasionally touching the bumper (probably from 255 Toyo RR), so I trimmed this area of the bumper on both sides with a dremel. This is undoubtedly from the caster setting, which shocks me to hear that the 96+ M3 can get up to +8 caster.... that kind of caster would cause issues with every 255 tire on the market & the front bumper... so I assume everyone is trimming the bumper slightly at the very least.

The overall diameter is below 25" on the RSRRs I run, this is purposely to avoid issues with the perches, fenders, and bumper. I always buy tires by actual measurements, and never by the arbitrary BS the manufactures assigns to them.

EDIT: I checked the specs of your Michelin Super Sports, and the overall diameter is 25" exactly (good), but your tires are a half inch wider in section & tread width compared to the tires I run. This will cause more problems with fitment on the front fenders, regardless of wheel width. I think the fix will be to run more negative camber, and less caster.

[TostitoBandito]

I'll have to check my latest alignment sheet, but my caster isn't that high on a 99 M3 with GC camber/caster plates. They're maxed out and if I recall I have around +6.5 or so on each side, or somewhere close to that. Never had any rubbing issues, though I also only run 17x9's with 245's.

[hc1001]

Thanks for the info guys. Anyone else?

Neverlift, Your wheels are poking out more than mine. My 9" wheels are ET51 with 15mm spacer, I raised the perch high enough to clear the tire sidewall. Perhaps your wider stance causes contact with the front bumper when turning the wheels?

FWIW, i found my old alignment sheet from 2006 when i had stock strut mounts/eibach prokit and koni shocks and it says 7.8 and 7.9 degrees of caster.

[Team Neverlift]

Ok, 13mm difference between our offsets once spacers are accounted for... that is basically .25" when split in half due to my wheels being .5" wider... so let's say 6.5mm more fender clearance.... but then your tires are .5" (12.7mm) wider than mine... I stand by my last fix calculations.

[hc1001]

Hmmm sorry, maybe i screwed something up but my calculations show the outer edge of your rim is 19mm further than mine. But yea, i am running a wider tire than you and tire manufacturers have their own unique way of tire sizing... so its not apples to apples and hard to get an exact # without actual tire width at the contact patch/threads. Heck, maybe your rubbing could just be from having softer springs allowing for more travel or something.

I do appreciate the discussion with you as its helping me understand if i need to add more neg camber and decrease caster to safely run this setup on the track. Id just hate to cut up the tire/smash the fender in the middle of a turn or worse, wreck the car.

Thanks.

[nick325xit 5spd]

Thanks for the info guys. Anyone else?

Neverlift, Your wheels are poking out more than mine. My 9" wheels are ET51 with 15mm spacer, I raised the perch high enough to clear the tire sidewall. Perhaps your wider stance causes contact with the front bumper when turning the wheels?

FWIW, i found my old alignment sheet from 2006 when i had stock strut mounts/eibach prokit and koni shocks and it says 7.8 and 7.9 degrees of caster.

ET51 with spacer? That makes no sense. That would mean the wheels are ET66.

[Team Neverlift]

Yeah, it seems people like to respond to me with random calculators when it comes to wheel & tire sizing around here. This is the second one today, lol. I don't think I am going out on a limb to point out that my wheels do not stick out 19mm further than yours, from the photos alone. That is a .5" difference between my very crude math, and what this calculator says. Maybe the truth is somewhere in the middle?

If you want to make the assumption that the sidewall will remain static while cornering, you might be alright. However, it moves 1/2-3/4" while cornering, & that's before the contact patch even begins to apply lateral grip.

In regards to tire mounted on wheel contact patch measurements, those are the measurements I used to find out how much wider your tire is than mine when mounted on our wheels (a random calculator; yes, I see the irony in using it, but is said to be compiled by user data)

Having said all of that, I use a local backroad with crazy cambered undulations & elevation changes to test my tire fitment throughout the entire compression stroke at low speeds. If one comes to mind for you, give that a try before the track and see how it goes... set up a GoPro in any problem areas to see exactly what is going on. This is what I do for all of my buddies who hardpark their cars, that never see the track, but ask me to roll and/or pull their fenders more.

[hc1001]

ET51 with spacer? That makes no sense. That would mean the wheels are ET66.

Hi Nick,

No... offset is the space between the mounting face of the wheel and the imaginary line that is drawn in the middle of the wheel width. My mounting face is on the same side as the outer half so its positive. ET51 means its 51mm away from the middle of the wheel. If i add a 15mm spacer, i am decreasing the space between the mounting face and the middle of the rim.

Hi Neverlift,
Not sure why you think its a random calculator. It shows the change from your rim to my rim, no tires are accounted. Its only showing the rim size change as well as our offsets.

Here is a simple example(first pic) of going from 8 to 9" wide rims that have the same offset. Would you not agree that both sides will increase .5"(13mm) as shown in mm?

Another example(second pic), If i used a 13mm spacer on the 9" wide rim, the offset changes to ET18 and pushes out the rim edge 13mm further. So the inner edge location(lets just say distance from strut assembly) of the 9" rim is the same as the inner edge of the 8" wide wheel but the 9" wide wheel is sticking out 26mm on the outer edge compared to the 8" outer edge.

By plugging in the offsets of our rim specs with spacers accounted for, the calculator shows your rim is sticking out 19mm more than mine. This is true only if the wheels specs you listed(9.5" wide with ET35 + 12mm spacer for total offset of ET23) are accurate. Unless my understanding of wheel offset is way off or did i forget to account for anything else?

[TostitoBandito]

Yeah spacers are simply a way of decreasing offset when it doesn't make sense or isn't possible to get wheels with the exact offset you need. An ET42 wheel with a 12mm spacer has an identical hub profile to an ET30 wheel, just with some metal and weight added in the form of a spacer.

[hc1001]

Wow... you guys are not calculating offset correctly... an ET30 wheel with a 12mm spacer is a ET18 wheel...

ET30 means the mounting face is 30mm away from the centerline of the rim. If you install a 12mm spacer, the spacer is the new mounting face. If you look at the left side of the calculator pics i posted, offset is the measurement between the centerline(vertical dash line) and the orange line. Stick a spacer in between and you decrease offset because the left side of the spacer is the new mounting face.

[TostitoBandito]

Wow... you guys are not calculating offset correctly... an ET30 wheel with a 12mm spacer is a ET18 wheel...

Yeah I know, I just spaced for whatever reason when I wrote my post, which has now been corrected. I should know, I'm running ET42 wheels with 12mm spacers in front to clear the struts and get closer to the fenders.

[Crustashio]

Adjusting caster at the top plate will do little to change the wheel position. You need to alter the position of the outer balljoint on the LCA to have a significant effect...this is why 95s use offset LCA bushings.

Also, reducing caster at the mount will actually move the wheel forward (although a tiny amount).

[Team Neverlift]

It is a random calculator because I do not know the formula or person who created it.

Yes, it all looks well and good with the 8 & 9 comparison, but 19mm difference does not pass the eye test. This is where this random calculator loses me, in a similar fashion to the comment above. It doesn't make any sense in my experience. =)

[hc1001]

Found the calculator here http://www.1010tires.com/Tools/Wheel-Offset-Calculator#

Crustashio, that makes sense to me since the LCA outer balljoint is the pivot point. My mistake on assuming a caster change at the plates would somehow relocate the pivot point. I overlooked that part...
Thanks for clearing that up with me. Saved me the hassle of changing the caster on the plates.

[BacDoc]

Quick question, is the caster adjustable on the '95 M without plates? I have camber plates and PF offset lollipops. I've having same issues as OP my 245/645's on 18x8.5's rubbing the edges of the front fender.

[Moron95M3]

^^no, not adjustable. Need plates, or to change LCAs/LCABs. (could always spin your offset LCAB to change caster! LOL...but really, it would work).

[BacDoc]

I was afraid of that. Thanks.

I still feel like plenty of people are running at least a 245 or bigger without problems.

[Moron95M3]

What camber plates are you running?

[BacDoc]

SPC. I just got off the phone with them. The lower plate can be turned to allow +/-.50 caster. :banana:

The SPC plates look juuuuust like the UUC ones.