[Sypher]

Spring is still a couple of months away in Canada but I'm starting to think about my wheel options for when the warm weather rolls around. My plan is to run 235/40/18 square Falken RT615k+ tires. For wheels, the ones I'm looking at comes in either 18x8 etc 40 or 18x9 et40. Does anyone know, or has anyone tried running 18x9 et40 40 all around? The suspension setup is stock with the exception of Superpro adjustable camber lower control arm bushing pushing the front camber out to -0.8° and Dinan shockware.

I know that 18x8 will work for sure but since I autocross the car often, I want to keep my options opened for if I want to upsize the tires in the future (with camber plate upgrade too of course).

[Anthony235]

18x9+40 with a 235 tire will be close with only -0.8 camber. If I was a betting man I would say it won't fit.

I would say you need at least -1.5 camber to get it to fit. Maybe -2.

But I wouldn't run a 235 tire on a 9" wheel.

[Sypher]

Hm, yea, I was afraid it probably wouldn't fit. I know rwalker said in some older posts that he was able to use 18x9 et41 with 255 tires on his track setup before, but I'm not sure if that was before or after he started to use camber plates (post was back in Jan 2015). Hopefully he can shed some light on his old setup.

As for 235 on 9" rims, that's not a problem. I've ran that before on my old car for years and know of miata guys who runs 225 on 9" rims (autocross guys, not stance/carshow guys) and prefers it because of the reduced side wall flex.

[aaaaah]

I know skitch was running Hankook RS4s in 245/40 square on 17x8 et40 with no issue.

[cxp213]

Yeah, 235s on 9" wheels are fine since you want a slight stretch to minimize flex and squirm, which you want for autox.

As for fitting a 9" wheel, I'd probably say that's not going to fit without a lot of negative camber and/or fender rolling. I'm currently running 235/40 on a 8.5" ET42, lowered 25mm, with -0.8º camber in the front. Stock shocks, no camber plates, no other suspension mods. That's the closest I can get to the unrolled fender without rubbing and there's literally about 5mm clearance between tire and shock with no load.

BTW, what SCCA class are you in currently? Also, if you're thinking of getting wider tires/wheels, what class does that move you to?

[Sypher]

Originally Posted by cxp213

Yeah, 235s on 9" wheels are fine since you want a slight stretch to minimize flex and squirm, which you want for autox.

As for fitting a 9" wheel, I'd probably say that's not going to fit without a lot of negative camber and/or fender rolling. I'm currently running 235/40 on a 8.5" ET42, lowered 25mm, with -1.7º camber in the front. Stock shocks, no camber plates, no other suspension mods. That's the closest I can get to the unrolled fender without rubbing and there's literally about 5mm clearance between tire and shock with no load.

BTW, what SCCA class are you in currently? Also, if you're thinking of getting wider tires/wheels, what class does that move you to?

Thanks for the info. Sound like it's probably not a good idea to try to run 9" just yet.

My local autox base classing loosely on SCCA rules, but we have our own classing (hence why I can get away with some camber). Normally the car will fall under F street but I think if I was to compete under true SCCA rules, the tires and camber adjustable bushing would've pushed it into STU.

[cxp213]

Originally Posted by Sypher

Thanks for the info. Sound like it's probably not a good idea to try to run 9" just yet.

My local autox base classing loosely on SCCA rules, but we have our own classing (hence why I can get away with some camber). Normally the car will fall under F street but I think if I was to compete under true SCCA rules, the tires and camber adjustable bushing would've pushed it into STU.

I was just about to say it sounds like you might get thrown into a class where you're not going to be competitive in, let alone with just tires/wheels, lol. None of the 2-series cars are really considered competitive in their respective SCCA classes, though. I was going to suggest just doing your own thing and have fun instead of trying to build to class rules, but that's what you're already doing so never mind.

[Sypher]

Originally Posted by cxp213

I was just about to say it sounds like you might get thrown into a class where you're not going to be competitive in, let alone with just tires/wheels, lol. None of the 2-series cars are really considered competitive in their respective SCCA classes, though. I was going to suggest just doing your own thing and have fun instead of trying to build to class rules, but that's what you're already doing so never mind.

At my local club, the 2 series is actually pretty competitive. I was consistently competing for class podium last year with a stock 228i. I know the 2 isn't a top competitor with it comes to SCCA though. Stickier tires should give me the little more edge I need

[Nugget]

I tried out my e36 track wheels which 17x9et42 with 245/40 R comps (which run very big).

Looks like it will just fit with a 12mm spacer needed on the front, but I didn't drive around on them so take with a pinch of salt, and I have -2 camber all around.

[Bee Pee]

Originally Posted by cxp213

I'm currently running 235/40 on a 8.5" ET42, lowered 25mm, with -1.7º camber in the front. Stock shocks, no camber plates, no other suspension mods.

How have you managed to get -1.7deg front camber with just -25mm springs ?

[pillowlow]

With 18x9 et44 and adding a minimum 9mm spacer, I am about the run 235/40/18 mpss with minimal polk at stock camber and height. But, adding a little camber will probably make the wheels flush with the fender.

[cxp213]

Originally Posted by Bee Pee

How have you managed to get -1.7deg front camber with just -25mm springs ?

Thanks for pointing that out. I was thinking of my rear specs. I just checked my alignment sheet and it shows the fronts are at -0.8º driver and -0.4º passenger with the springs.

[Sypher]

Originally Posted by pillowlow

With 18x9 et44 and adding a minimum 9mm spacer, I am about the run 235/40/18 mpss with minimal polk at stock camber and height. But, adding a little camber will probably make the wheels flush with the fender.

So you have a combined et53? That looks like way too much poke especially if I were to run a RT615K+ which runs wider than the MPSS.

[Bee Pee]

Originally Posted by cxp213

Thanks for pointing that out. I was thinking of my rear specs. I just checked my alignment sheet and it shows the fronts are at -0.8º driver and -0.4º passenger with the springs.

wow 0.4 deg difference between L&R is too much imho

[aerobod]

Originally Posted by Sypher

So you have a combined et53? That looks like way too much poke especially if I were to run a RT615K+ which runs wider than the MPSS.

ET44 with a 9mm spacer would combine to give ET35. The spacer is needed to clear the strut. You may have slight poke, but it is unavoidable with a 9” wide wheel without using camber plates.

[Sypher]

Originally Posted by aerobod

ET44 with a 9mm spacer would combine to give ET35. The spacer is needed to clear the strut. You may have slight poke, but it is unavoidable with a 9” wide wheel without using camber plates.

Ah, I thought he meant ET44 with another 9mm spacer. Though it looks like more than just a slight poke. I'll refrain from the 9" width for now until I decide to get camber plates.

[Shadowfax028]

Originally Posted by Sypher

Ah, I thought he meant ET44 with another 9mm spacer. Though it looks like more than just a slight poke. I'll refrain from the 9" width for now until I decide to get camber plates.

So guyz help me understand. If I would like to run a 18 x 9 squared set up with out the necessity of spacers What offset is needed?

Or is this even possible. My current car is a 2016 M235i

[Sypher]

Well, if you go by what pillowlow said, it can be done with about ET44 offset. Running wider tires than 235 will need more camber than stock provides though.

[Sypher]

To cap off my own thread, I ended up ordering the 18x8 et40 (Fast Wheels FC04 flow formed wheel in matte bronze). I just test fitted them today and looks like everything will be good to go. It's likely that 18x9 et40 would've fit the front but just barely (possibly some rubbing). There's 20mm of space between the rim and the strut, and an online calculator says that 9" wide et40 would sit 13mm closer to the strut and poke 13mm out. Though, I'm not sure if there would be any issues with the back. Only tested the front.

Now I just need the warm weather to come...

[Shadowfax028]

I spoke with Apex Racing, they indicated the time might be right fir a special run for a 18 x 9 rim combined with a spacer for the front. It would offered as a group buy.
The caveat would be that enough people would need to commit for it to happen.