HELP! Autocross wheel/tire setup on 135i

[nje82]

I just picked up a 2009 Stage2+ 135i manual (stock turbos, stock'ish suspension) and I want to get it prepped for the autocross season in New Jersey. I'm not uber competitive and don't race SCCA so adhering to the rigid classing restrictions isn't really a concern to me. I'm struggling to find a square or staggered set of tires that are reasonably competitive and reasonably priced.

Based on my research on this forum and what I can find on the market I ended up with two options:

Staggered - Apex Arc 8 wheels
Front: 18x8.5" ET45 with 235/40-18 tires
Rear: 18x9.5" ET58 with 265/35-18 tires
I simply can't find a good 200AA or R comp tire in these sizes that is actually in stock. The Azenis RT615K seem like a grippy choice on a budget, mixed reviews though. The Kumho V720s would be my pick but they aren't rated for track use. Tirerack search
Tires: AZENIS RT615K+ F: 235/40R18 R: 265/35R18

Square Setup - seems like this is the way to go to defeat understeer properly. However i'm also likely pushing 380rwhp+ so a 265 rear would be more suitable to put down the power on corner exit.
Apex Arc 8 Front & Rear: 18x8.5" ET45 with 235/40-18 tires
I found a set of never installed Toyo Proxes R888R 235/40/ZR18 for $850, pending confirmation.

Current wheel setup is Style 261s which are 18 x 7.5 +49
18 x 8.5 +52 with standard all season tires that dont current hookup in 1st/2nd. Is the front wheel too narrow for a 235 tires to run a square setup?



The relevant mod list:

Wagner Tuning Evo II Competition Intercooler
Fully built WaveTrac LSD + Whiteline rear subframe and differential carrier bushings (going in next week)
VRSF 3″ Cast Stainless Steel Catless Downpipes
REMUS Sport Quad Exhaust System (stock resonators / mid pipe)
VRSF Charge Pipe
AEM Methanol Injection Kit (not installed)
VRSF Relocated Silicone High Flow Inlet Intake Kit
201-0121 coil n54 kit
stock turbos, stock suspension

Super helpful page on this forum - 1 series fitment guide: https://support.apexraceparts.com/hc...-Fitment-Guide

Any advice would be greatly appreciated!

[amsnow440]

If it's a dedicated autox setup and you're going square, have you considered 17" wheels? Check out a 245/40-17 set of the new falken rt660, should be under $700 for the set.

Apex makes the arc8 in 17x8.5 +40 which should work for you.

[BronkaidBrah]

Is nj bringing back autox events finally!?! U made me a happy dude if true. hpde "limited covid" events are getting ridiculous with their pricing for having no instructor student time and only lead follow. Are you currently on near stock suspension? If so running the apex wheels with the recommended sizes on the site is the way to go , they know their shit. My personal favorite setup however has not been square but staggered A052 225/35/18 fronts on 8" wheels and 255/40/18 on 9" wheels out back.it probably won't help you much since my suspension is highly modified but I also run -3 degrees camber up front -2 rear 1/8 toe out front for autox 3/16 toe In at rear. Makes the car feel neutral enough during exits and super quick on turn ins. Gets a bit squirrelly sometimes though since it can be pretty tail happy.

[nje82]

Originally Posted by BronkaidBrah

Is nj bringing back autox events finally!?! U made me a happy dude if true. hpde "limited covid" events are getting ridiculous with their pricing for having no instructor student time and only lead follow. Are you currently on near stock suspension? If so running the apex wheels with the recommended sizes on the site is the way to go , they know their shit. My personal favorite setup however has not been square but staggered A052 225/35/18 fronts on 8" wheels and 255/40/18 on 9" wheels out back.it probably won't help you much since my suspension is highly modified but I also run -3 degrees camber up front -2 rear 1/8 toe out front for autox 3/16 toe In at rear. Makes the car feel neutral enough during exits and super quick on turn ins. Gets a bit squirrelly sometimes though since it can be pretty tail happy.

Yes.. check out https://www.autox4u.com/calendar/ i usually run MotorsportsNE as they offer tons of runs. usually 8+ runs and once in a while they run an autocross school in the morning and standard autocross in the afternoon. this gets you over 25 runs for the day which is a LOT of seat time.
come out and play!

[nje82]

Originally Posted by amsnow440

If it's a dedicated autox setup and you're going square, have you considered 17" wheels? Check out a 245/40-17 set of the new falken rt660, should be under $700 for the set.

Apex makes the arc8 in 17x8.5 +40 which should work for you.

Yes the -1 option sounds great for autocross.. the setup would be 1" shorter than the 18" setup. i having a smaller circumference is better for autocross on this car, no? I found the tires, but on backorder.. https://www.tirerack.com/tires/tires...omCompare1=yes will a 245 tire fit up front on stock suspension? i thought the max are 235s, then need to roll fenders and max negative camber.. if not this would be a great option..

[b1aze]

Originally Posted by nje82

Yes the -1 option sounds great for autocross.. the setup would be 1" shorter than the 18" setup. i having a smaller circumference is better for autocross on this car, no? I found the tires, but on backorder.. https://www.tirerack.com/tires/tires...omCompare1=yes will a 245 tire fit up front on stock suspension? i thought the max are 235s, then need to roll fenders and max negative camber.. if not this would be a great option..

The 245/40/17 is NOT a 1” shorter than stock. Yes the wheel itself is smaller diameter but the tire sidewall makes up the difference. 24.7” is the general diameter of the 245/40/17 when stock is 25”. Well within the 3% suggested allowance range.

There’s a whole thread about fitting 245 square on these cars in the suspension subforum. Give that a read, it should answer all your questions.

[nje82]

Originally Posted by b1aze

The 245/40/17 is NOT a 1” shorter than stock. Yes the wheel itself is smaller diameter but the tire sidewall makes up the difference. 24.7” is the general diameter of the 245/40/17 when stock is 25”. Well within the 3% suggested allowance range.

There’s a whole thread about fitting 245 square on these cars in the suspension subforum. Give that a read, it should answer all your questions.

OK. checking the #s you are absolutely correct.. looks like i was comparing the 235 18 to the 245 17. i'll check the suspension thread, sounds like the perfect option. thanks!

245/40ZR17 - 24.8"
235/40ZR18 - 25.4"
215/40ZR18 - 24.8"

[nje82]

Originally Posted by b1aze

The 245/40/17 is NOT a 1” shorter than stock. Yes the wheel itself is smaller diameter but the tire sidewall makes up the difference. 24.7” is the general diameter of the 245/40/17 when stock is 25”. Well within the 3% suggested allowance range.

There’s a whole thread about fitting 245 square on these cars in the suspension subforum. Give that a read, it should answer all your questions.

do you have a link? i tried searching and checked the stickies but dont see it. there are a few threads on 17s but can't seem to find anything exhaustive on tire options that is current.

For my application, can i squeeze a 245/40/17 tire on the arc8 in 17x8.5 +40 up front without rubbing? With stock suspension is front camber adjustable enough to get to -2, -2.5 or do i need camber plates or m3 arms? thanks in advance!

[lakefront]

Lots of great information on the racing subforum as well. Some very successful autoxers there.

[iminhell1]

Tire Rack isn't the only tire dealer on the internet ...
And 17's is where it's at.

[b1aze]

Originally Posted by nje82

do you have a link? i tried searching and checked the stickies but dont see it. there are a few threads on 17s but can't seem to find anything exhaustive on tire options that is current.

For my application, can i squeeze a 245/40/17 tire on the arc8 in 17x8.5 +40 up front without rubbing? With stock suspension is front camber adjustable enough to get to -2, -2.5 or do i need camber plates or m3 arms? thanks in advance!

https://www.1addicts.com/forums/show....php?t=1785918

[Converted1]

Good to hear about others enjoying their 1s with autox. I’ve been doing the Metro PCA events held out at Tobay Beach in Long Island. They are well run and enjoyable events. I’m not super competitive so I run my stock set up with altered tire pressures. There is usually a white 1M there although It might be a conversion.

[jw.e36]

To answer one of your questions, I ran a 235/40 on my 261's and it was no problem at all, definitely not too narrow. As for square, I actually ran a 245/45/17 (same height and width of a 245/40/18) square setup last year for my track setup (would have preferred a 40 sidewall but I couldn't pass up the deal on the 45's) on a set of 17x8 +47 oem style 96's that I had laying around, no fender modification, lowered on Eibach pro-kit springs. Only issue I ran into fitting that setup was a tiny bit of rubbing on the front struts, but a 5mm spacer took care of that. Its tight up front, but it fits with no rubbing.

[nje82]

UPDATE: Ordered a set of 17x8.5" APEX Arc8 wheels https://www.bimmerworld.com/Wheels-T...C-8-Wheel.html and Bridgestone RE71r tires from discounttire.com
Should be here in a week!

[chris82]

Originally Posted by amsnow440

If it's a dedicated autox setup and you're going square, have you considered 17" wheels? Check out a 245/40-17 set of the new falken rt660, should be under $700 for the set.

Apex makes the arc8 in 17x8.5 +40 which should work for you.

I have those apex 17x8.5 +40 offset wheels with hankook RS4 235/45 tires in back. I'm lowered with -2.8 camber and they still rub on big dips. Forget anything wider than that in the back without major fender rolling. Stock suspension might be different but on a lowered car that is not a plug and play fit despite what apex says. I'd go 17x8.5" et45 next time

[CrashT]

I don't have any advice--just want to say welcome to NNJR. There are a few 1ers running this year, all in STU I believe, all bc our cars need a tune to really come alive. See you at Pocono?

-No. 53

[nje82]

Originally Posted by chris82

I have those apex 17x8.5 +40 offset wheels with hankook RS4 235/45 tires in back. I'm lowered with -2.8 camber and they still rub on big dips. Forget anything wider than that in the back without major fender rolling. Stock suspension might be different but on a lowered car that is not a plug and play fit despite what apex says. I'd go 17x8.5" et45 next time

Thanks Chris! I don't have any plans to lower the car, can't you just use 5mm spacers? or am i backwards?

[nje82]

Originally Posted by CrashT

I don't have any advice--just want to say welcome to NNJR. There are a few 1ers running this year, all in STU I believe, all bc our cars need a tune to really come alive. See you at Pocono?

-No. 53

Thanks for the welcome! I usually autocross with motorsportsne.com. There is an upcoming June Friday event that I'm hoping I can make assuming i get a few issues fixed and get the wheels/tired mounted and car aligned in time. test and tune in the morning and autocross in the afternoon. Definitely interested in a HPDE day, for now need to get the car sorted. Where are you based out of?

[smi2710]

I have run my 135i at a few autocross events. I started with the bmw club in NNJ then did a few laps with the NJSCCA, while the bmw group was for fun scca was as well but I was not competitive in my class STU. I am lowered , tuned etc... I was running stock wheels and indy firewak 500's in the rear and a all season up front. This year i have added the firehawk 500's in the front and hope to get out to a few days this year, tire size is 225 F and 255 rears. The only thing I would say is I ran faster times with no tune set and traction off. with a tune I needed to run half my traction off. Over all I ran better faster times with stage 2 turned off.

[dtla1]

Originally Posted by chris82

I have those apex 17x8.5 +40 offset wheels with hankook RS4 235/45 tires in back. I'm lowered with -2.8 camber and they still rub on big dips. Forget anything wider than that in the back without major fender rolling. Stock suspension might be different but on a lowered car that is not a plug and play fit despite what apex says. I'd go 17x8.5" et45 next time

APEX was working on a 17" fitment for a square setup, but I don't remember the offset right now. They test fit it on my car front and back with 255/40 Nittos. Hopefully they come out with them soon.

[chris82]

Originally Posted by dtla1

APEX was working on a 17" fitment for a square setup, but I don't remember the offset right now. They test fit it on my car front and back with 255/40 Nittos. Hopefully they come out with them soon.

I hope so! I think there needs to be a 17x8.5 et45 offset. That way you can run a square setup with a nice fit in the back, and then add a 5-10mm spacer in front if needed to decrease your offset.

[chris82]

Originally Posted by nje82

Thanks Chris! I don't have any plans to lower the car, can't you just use 5mm spacers? or am i backwards?

You got it backwards. I also had it backwards until I see my wheel/tire pushed too far out and realize a spacer could never fix this