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Technical Discussion

Concavity on the E36 and E36 M3!

Article | 12/13/2012 by Tom Maloney

ARC-8, 17X9.5” ET35

This is the most aggressive 17″ wheel fitment available from Apex for the BMW E36 and E36 M3. Because of the wheel’s concavity it is most commonly used as a street fitment with slightly undersized tires: 245/40/17. This fitment can be easily adapted for track and autocross with wider or more aggressive tires using proper specifications and precautions; see below.

SPECIFICATIONS

The specifications are meant to help you understand why and how this fitment works. Some of the information may seem inconsequential but we have seen fitments not work because of what would normally be considered foregone conclusions, such as rear camber:

A customer couldn’t get a known, easy fitment to work and we went back and forth for weeks only to find a mechanic had set their rear camber to 0. On their E46 non-M, stock camber in the rear is -2 degrees. The 0 degree camber caused rubbing on the fender and there was no way for us to know.

This fitment article is not referencing a specific car so the specifications are general.

  • Car/chassis: E36 M3
  • Wheel model: ARC-8
  • Wheel size: 17X9.5” ET35
  • Spacers: 5 MM spacers in front. A wider spacer may be necessary depending on strut type
  • Tires: 245/40/17s or 255/40/17s with additional rear fender modifications
  • Suspension: Stock style front struts. Coilovers with 5″ or 6″ main springs and no helper springs. Conical, progressive springs cannot be used with this fitment either.
  • Camber plates: Required.
  • Alignment: -3 front and -2 rear camber This setup will also require aggressive camber if using a 255 tire.
  • Fenders: Rear fenders rolled and shaved. If you are using a 255 or a meaty 245 you will need to pull the rear fenders. Although Depending on your tire choice/size, you may need to shave the inside of the of the rear fender where it meets the wheel arch.
  • Other body modifications: None
  • Brakes: OEM. We do not recommend big brakes with this fitment as the spacers required would push the wheels too far out.

ADVICE:

Important to know, the wheel extends out 13mm more than the 17×9″ ET42 setup in the rear. Those measurements give you an idea of how much more fender rolling and, potentially, pulling is required when using this wheel setup over the 17×9″ ET42.

Strut side clearance in the front is extremely close. The 17×9.5″ ET35 with a 5mm wheel spacer is 6mm closer to the strut than a 17×9″ ET42 with a 12mm wheel spacer. Even with the 5mm wheel spacer spring perch location with coilovers is very important. Make sure that the spring perch is above the wheel and tire.

Vital to this fitment working is the front suspension and the inner clearance. The lower spring perch must be above the tire so you are only clearing the strut tube and not the wide perch. Some coilovers utilize a helper spring which sets the lower spring perch too low and next to the tire, not above it. This will limit your tire width possibilities and requires a thicker than recommended spacer which will push the wheel too far out. If this is an issue with your existing suspension you can remove the helper springs and/or raise your ride height.

FENDER MODIFICATIONS: ROLLING, SHAVING, AND PULLING

The rear fenders do need to be rolled but not necessarily pulled for this size. The area of contact that is the worst is where the rear bumper meets the wheel arch. Focus on that area with your fender roller the most and you may need to do a little shaving on the inside of the bumper.

Pulling will be required if you choose to run a 255 or a meaty 245. If you choose to have your rear fenders pulled, consult a body or performance shop that is experienced in doing this.

SUPPORT

As always, feel free to email us at info@apexraceparts.com or call us at (925) 245-0773 with any questions you may have. We can walk you through fitment potentials for your car and make sure you get all of your questions answered.

Tags
  • Bolt pattern: 5x120mm
  • Fitment type: Aggressive Street
  • BMW, M3, E36
  • BMW, 3 Series, E36
  • Wheel design: ARC-8
  • Wheel diameter: 17"
  • Wheel line: Flow Formed Classic Line

Tom Maloney

Tom M.

Tom is a BMW Fitment Expert at APEX Wheels. Prior to joining the company in 2019, he worked for BMW of North America as Fleet Manager: Portland (OR) for the ReachNow car-sharing program, and as Warranty Administrator/Loaner Fleet Manager at BMW Portland. In addition, Tom has extensive training in BMW TSBs (Technical Service Bulletins) as well as in-depth knowledge of all BMW chassis and their wheel fitment options, with and without aftermarket brake and suspension upgrades. His high-performance driving experience includes autocross events in southern Oregon and track days at PIR in his 2004 E46 330i with 17x9 ET42 APEX ARC-8 wheels. Vehicles he owned prior to indulging his passion for BMWs include a 1989 Jaguar XJ6 and a 2006 S197 Ford Mustang. Fun Fact: Tom is a huge Formula 1 fan. Have questions about wheels for your BMW? Use our contact form and ask for Tom.