315/30/18 mounted, fitted and not rubbing

[Bryson]

2/12 Update: See post #25 for more info, currently testing et24/21 to eliminate any rubbing under extremely hard cornering.

3/23 Update: Tested et21 (6mm spacers) and I cannot get it to rub anywhere, no matter how hard I try. Sounds like we've got it settled, 18x10.5 et21 and 315/30/18 are a go!


Original Post below:
Finally did it.. had the 315s mounted up to my 18x10.5 wheels and removed the spacers for a completely touch free fitment. With my rolled fenders, there is about 5mm clearance to the fender and slightly less to the inner liners and thrust arm. I may even add spacers to fill out the wheel well. I think it would look best with trimmed fenders and 10mm spacers, I hate to give up that great look that the car had with 285s, but onward and upward! Next step is 295/30/18 fronts

So for those looking to fit 315s on the back of their 8, you must use an offset between 28mm and 24mm for best results (pictured here is et 27mm). If you have 28mm offset, you may be able to get away without rolling your fenders, but any lower and you'll need to just finish the stock roll that the factory started. Nothing major by any means.

Enough talking, here's what you came for..















I'll try for some better photos in the next few days with everything all cleaned up.

Bryson

[Major Cheese]

That's a lot of rubber! I like the looks(angle) in pic #3.

[Auraraptor]

Love it.

[crazy8]

Awesome man! That's some phat meat on there!

[8eights]

I like fat, That's Fat! Pic 3 & 4 are killer.

[taylorpatterson]

I'd never have believed it if I hadn't seen it with my own eyes!

[moonfresh]

YES! You are my HERO! I was hesitant about 10.5 wheels. I was waiting for you to do it first. I am going to get my wheels expanded now. Do you notice anything different, in terms of handling?

[Bryson]

Thanks guys! Just took it out for a little bit to get the dry layer off of the rubber, even hard throttle on right turns, the car just digs

Love it.

You're next..

Awesome man! That's some phat meat on there!

I like fat, That's Fat! Pic 3 & 4 are killer.

The resident steamroller! Pictures don't do it justice.

I'd never have believed it if I hadn't seen it with my own eyes!

I'm sure you'll be seeing it up close some time in the near future

YES! You are my HERO! I was hesitant about 10.5 wheels. I was waiting for you to do it first. I am going to get my wheels expanded now. Do you notice anything different, in terms of handling?

Nothing real different in terms of handling from the 285s, though these need a couple more psi than the 285s did to feel balanced. Currently I'm running 34F/36R and that seems pretty good. If you can choose your offset, I'd shoot for 25mm (or 1" - 25.4mm) and definitely have your fenders slightly rolled. Also, if you put the 9" wheels up front, I'd recommend a 265/35/18 tire for those. Cam you made this happen, thank you!!

[CaifanSC]

oh snap! my rear hamanns are 10.5..sawweeeet!

[mojocoggo]

YES! That looks amazing. Whatsup supercar.

[Imndeep]

picture 7 is amazing, I can't believe you have that much clearance with those 315's. Hmmm, I hate when you get me thinking. My ET is already 20mm, I've heard that you don't want to mess with Spacers under 10mm. Looks like I can't do it

[wokke]

.........I've heard that you don't want to mess with Spacers under 10mm. Looks like I can't do it

Reason for this is the centering issue. Had this issue on a set of 10" ALPINAs ET28 which went on an E24.
I mounted a set of 10mm spacers permanently to the rim after centering it first with a special tool which I had made up.

[Koizumi]

Now that looks great Bryson. I wonder if my Alpinas would let me do something similar.

[Ryako1]

Now THAT is VERY sweet!!!!!!!!!

[Bryson]

oh snap! my rear hamanns are 10.5..sawweeeet!

picture 7 is amazing, I can't believe you have that much clearance with those 315's. Hmmm, I hate when you get me thinking. My ET is already 20mm, I've heard that you don't want to mess with Spacers under 10mm. Looks like I can't do it

Now that looks great Bryson. I wonder if my Alpinas would let me do something similar.

If your offsets are in the range of ~24-28mm and your wheels are 18x10.5, this should work for you. If your offsets are higher, you can use spacers to bring them down into acceptable range. With an 18x10.5 et20, you'll definitely need to trim the inside of the fenders like Forrest has done to his e31 with spaced out MK1's.

Now THAT is VERY sweet!!!!!!!!!

Thank you!

Reason for this is the centering issue. Had this issue on a set of 10" ALPINAs ET28 which went on an E24.
I mounted a set of 10mm spacers permanently to the rim after centering it first with a special tool which I had made up.

Very trick setup Wolf! Maybe I'll end up doing the same..

[CaifanSC]

With an 18x10.5 et20, you'll definitely need to trim the inside of the fenders like Forrest has done to his e31 with spaced out MK1's.

Ha! great...i just checked the old post for the guy who sold me the rims and they are 10.5 et20

I guess if I want to go into the 300's in the rear I need to roll the fenders.

[Bryson]

Bummer! All hope is not lost.. Head to your local body shop and ask them about trimming the lip off your fenders to clear the bigger tires, they should be able to help. IIRC, Forrest's were pretty reasonable

[Imndeep]

If you trim the rear inner lips won't you separate your inner wheel housng fron your quarter panel? That is exactly what happened when I trimmed my inner lips to fit in Mickey Thompson 28-12X15's on my '68 Road runner. Maybe The 8er has different wheel housing construction?

[Auraraptor]

Bryson, if your running PS2s, note their sidewalls are VERY sensitive to vehicle weight/loading.

I ran 275 and 295 PS2s on my 8 and 305 PS2s on my heavy Benz very briefly, and all had sidewall-flex-under-load issues....under extreme load (low gear + full throttle torque), the whole rear would shudder right to left as the sidewalls flexed under the extreme load. It was not a wheel balance issue, as the vibration was specific to only under extreme loading and absolutely fine otherwise/at any speed.

I am not the only one, its very well established on the benz forums: http://mbworld.org/forums/sl55-amg-s...ad-tranny.html

I found running than typical higher pressures helped to maintain it a bit better. In the end, switching to a hard compound tire from a soft compound fixed everything and my grip skyrocketed vs the narrower rears I used to run.

[Bryson]

If you trim the rear inner lips won't you separate your inner wheel housng fron your quarter panel? That is exactly what happened when I trimmed my inner lips to fit in Mickey Thompson 28-12X15's on my '68 Road runner. Maybe The 8er has different wheel housing construction?

I can't comment directly as I've never done it myself, but both Forrest and Ralph R have had it done on their cars and didn't mention anything regarding panel separation. Maybe Forrest will catch this thread and can add some insight.

Bryson, if your running PS2s, note their sidewalls are VERY sensitive to vehicle weight/loading.

I ran 275 and 295 PS2s on my 8 and 305 PS2s on my heavy Benz very briefly, and all had sidewall-flex-under-load issues....under extreme load (low gear + full throttle torque), the whole rear would shudder right to left as the sidewalls flexed under the extreme load. It was not a wheel balance issue, as the vibration was specific to only under extreme loading and absolutely fine otherwise/at any speed.

I am not the only one, its very well established on the benz forums: http://mbworld.org/forums/sl55-amg-s...ad-tranny.html

I found running than typical higher pressures helped to maintain it a bit better. In the end, switching to a hard compound tire from a soft compound fixed everything and my grip skyrocketed vs the narrower rears I used to run.

Interesting.. I'm really hoping that they release the PSS in this size, as I would definitely opt for that if it were available. When I tried 34psi all around, I noticed a considerable difference from 36, which substantiates what you're saying. I did try 40psi, but that was much too high. At that pressure, they translated a lot of NVH and the grip wasn't that great either. Perhaps I'll try 37 or 38 and see how they feel.

[Auraraptor]

I agree, a PSS would rock. I ended up running 305/30-19 RE11 on the benz, and it fixed the issue like a charm....no more wiggle. I have not yet decided what I am going to run on my (eventual when I actually buy it) 8 in terms of tires. It really depends what I can get in terms of the size I want when I am actually buying. Hopefully the available options increase by then.

BTW, keep note of how the sidewalls look as well as you tinker with pressures. If they are getting that 'glossy' shine, chances are the sidewalls are flexing so much they are bearing actual vehicle load under extreme deflection. The last thing you want is a sidewall blow out on a high G turn.

I think I settled with 37 when I was running PS2s on back of the 8.

Actually I take that back, I *know* my desired tires:

265/35R18 on a 9in (or wider) Front
295/30R18 on a 10.5 (or wider) Rear

Tire: Yokohama AD08 (Super stiff sidewall, AX semi-race tires).

Now I just have to find wheels I actually like that meet my size requirements! LoL *sigh*

Its not even a style issue either....I need to find wheels that will actually clear the brakes I am designing for the car as well. *sigh*

[Bryson]

Haha, decisions, decisions. Why not a 315/30 instead of a 295/30 out back? Purely tire selection? If the PSS were available, would you opt for that? a 9" with 265 will fit very easily in front, I'd recommend a 9.5 since I'm sure you'll be running some form of camber plates.

Do you think I should cut down to a 10" front wheel for a 295/30? It would bring the scrub radius in 1/4" and have a better F/R track balance now that I don't have spacers out back.

What are these super secret brakes you speak of? I've been wanting to use an OTS M floater and some sort of monoblock caliper for a while now. Also not opposed to using an OTS single pot caliper with custom bracketry..

[X5X]

I have to get a set of wheels before I can start thinking about this mod But its on my list for sure!

[Auraraptor]

Haha, decisions, decisions. Why not a 315/30 instead of a 295/30 out back? Purely tire selection? If the PSS were available, would you opt for that? a 9" with 265 will fit very easily in front, I'd recommend a 9.5 since I'm sure you'll be running some form of camber plates.

It is tire selection. If they did make PSS, I would opt for those instead, but I am not holding my breath. (Then again, by the time I actually get another 8, who knows? Maybe they will make them). In general, I opt for RE11>PSS>AD08s>others. The other starts depending on application. Case in point, I really like Conti DWs for rears.

I agree in terms of wheel sizing, but I am not too picky as I already have some rather specific needs, with low selection of options.

Do you think I should cut down to a 10" front wheel for a 295/30? It would bring the scrub radius in 1/4" and have a better F/R track balance now that I don't have spacers out back.

Personally, I would if its easy to source the wheels. Not only is the scrub radius better, but the tire will be a hair taller in the front now too (as it will be mounted on a narrower wheel), so your basic understeer/oversteer balance will be nicer...all while slightly decreasing unsprung weight.

What are these super secret brakes you speak of? I've been wanting to use an OTS M floater and some sort of monoblock caliper for a while now. Also not opposed to using an OTS single pot caliper with custom bracketry..

The brakes have been a side project for a while now. I have been working on a kit for my E38 and now that's just about done, I will focus on the 8 again....

I don't want to give details until its formalized/complete...but feel free to PM/call me and we can chat at length.

I will say as with everything I do, the kit will be optimized for the E31 in terms of brake bias and pedal feel. I have pages with calculations and an empty bank account from the various calipers+rotor combinations I have tried....

[Bryson]

UPDATE, it appears that I hadn't heeded the advice given below well enough before taking the car out for some serious corners. Well, after about 30 miles of driving and a few hard offramps, I've found that the tire deflects so much on the rim that it actually rubs on the control arm and inner fender well. I measured about 5mm clearance to the inside, so I thought that this was plenty, but I was mistaken!! This tire sidewall deflects at least that much when mounted on a 10.5" wheel..

Now what I've done to rectify the situation is buy 3mm and 6mm spacers. Currently, I've put on the 3mm spacers but haven't hit any hard corners as it's been raining. I can however report that there is no fender contact on full compression with them on. So that means that et24 with rolled fenders is still enough to clear. With trimmed fenders, it looks like et21 or even so far as 18 can still clear. This also gives hope that you could run an et22 18x11" wheel with this tire (less sidewall deflection) in combination with trimmed fenders. It would be close but should work.

I am now recommending an offset of 24mm, possibly even lower if need be. I'll keep this thread up to date as I get some more 'testing' done.

Bryson, if your running PS2s, note their sidewalls are VERY sensitive to vehicle weight/loading.

I ran 275 and 295 PS2s on my 8 and 305 PS2s on my heavy Benz very briefly, and all had sidewall-flex-under-load issues....under extreme load (low gear + full throttle torque), the whole rear would shudder right to left as the sidewalls flexed under the extreme load. It was not a wheel balance issue, as the vibration was specific to only under extreme loading and absolutely fine otherwise/at any speed.

I am not the only one, its very well established on the benz forums: http://mbworld.org/forums/sl55-amg-s...ad-tranny.html

I found running than typical higher pressures helped to maintain it a bit better. In the end, switching to a hard compound tire from a soft compound fixed everything and my grip skyrocketed vs the narrower rears I used to run.