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[Agetec]

Hey guys, so I've spent some time searching the forums about a fitment question I have regarding 18x10.5 ET 23 275/35/18 or 295/35/18 with a 5mm spacer on the front and 18x11 ET 30 305/35/18 on the rear. I planned on running BC Racing BR Series Coilovers with the front endlinks. Most of the information I have tells me this will work but i'm getting mixed information aswell and I would like clarfication on this as I rather not waste alot of money.

Thank you for your time.

[M43S7RO]

Rear "should" be no problem, 305/30 rear helps your odds. Front is gonna be tough without lots of camber and liner rub. If you dont want to rub, you'll have to remove liners or use less steering, or smaller tires obviously. This is all also very tire dependent as they all have variation that effects how they fit.

When going aggressive you have to be ready for trial and error and cost associated. Dont wanna play?? Go more conservative with a combination that works.

See here for an example of 295/30 up front:
https://www.m3post.com/forums/showthread.php?t=1704931

I'm waiting on 18x11 et30 wheels, I'm sticking to 285/30 fronts because I'm pretty sure I'd need to pull the liners if I went with 295/30. I dont want to destroy my liners or pull them out. Even then I'm ready for the possibility of needing to step down to 275s. I run 275/30 ad08r now up front on 19x10 wheels with acceptable to me rub on lock.

[Agetec]

Originally Posted by M43S7RO

Rear "should" be no problem, 305/30 rear helps your odds. Front is gonna be tough without lots of camber and liner rub. If you dont want to rub, you'll have to remove liners or use less steering, or smaller tires obviously. This is all also very tire dependent as they all have variation that effects how they fit.

When going aggressive you have to be ready for trial and error and cost associated. Dont wanna play?? Go more conservative with a combination that works.

See here for an example of 295/30 up front:
https://www.m3post.com/forums/showthread.php?t=1704931

I'm waiting on 18x11 et30 wheels, I'm sticking to 285/30 fronts because I'm pretty sure I'd need to pull the liners if I went with 295/30. I dont want to destroy my liners or pull them out. Even then I'm ready for the possibility of needing to step down to 275s. I run 275/30 ad08r now up front on 19x10 wheels with acceptable to me rub on lock.

Ok sweet I planned on running atleast -3 camber and if needed removing my liners. those tire sizes sound way more pleasant.

[Richbot]

The front doesn't have any wiggle room on larger than stock diameters once you go wider than stock. So you want a 285/30, 295/30 or 275/35-18 up front. A 295/35-18 will not fit up front without pretty significant changes to the unibody, I've tried it, it hits everything. A 295/30-18 ought to be fine with appropriate wheel, I've also done that.

Removing the liners doesn't fix the body seam at the rear of the wheel well up front.

[ApexWheels]

Is this a setup for street use, or will it see track time?

If your goal is to run 305/35-18 out back, then 275/35-18 would be the best match for the front. The two popular tire choices that I am aware of in those sizes are the Nitto NT01 and Toyo R888R, and we strongly prefer the NT01 for track use. I am not familiar with any street tires that are offered in these sizes.

18x10.5" Front Fitment Notes:

Fitting 18x10.5" wheels under the front fender arches is a balancing act between the following:

• Selecting wheels with an appropriate offset
• Dialing in the appropriate amount of negative camber
• Taking into consideration the intended tire size and model (not all are created equal)
• Taking into consideration your existing or future suspension silhouette and spring stack height

Even with all of the above dialed in, enthusiasts considering 10.5" wheels with a track-oriented compound should expect some light scrubbing around the liners under suspension compression or at steering angle - Par for the course for fast lap times.

The ideal offset for a 10.5" wheel on the front of an E9X M3 is typically between ET17 and ET22. The higher the offset within that range, the less negative camber you are forced to run to clear the fender arches. Most hardcore track guys running 10.5" wheels up front are already running somewhere around -3.5º, so dialing in negative camber shouldn't really be a barrier. We chose to produce our 10.5" wheels for the E9X M3 chassis with an offset of ET22, and since many will run these wheels in the rear as a part of a rotatable square setup or as a staggered setup, anything lower than an ET22 would limit rear tire width due to rubbing the rear fenders.

Beyond using the correct wheel offset, the silhouette and stack height of the suspension is equally important. Motorsport oriented coilovers like JRZ and MCS with 5" linear springs work very well, and depending on the stack height helpers springs may or may not be used. The idea is to keep the lower spring perch above the tire where it does not impede clearance. With a suspension setup like this and approx. -3.5º of camber, 18x10.5" ET22 (or lower) can accommodate 295/30-18 compounds without spacers under the front fenders.

Other popular coilovers like KW and Ohlins R&T are known for eating up inner clearance, and will require spacers or will need to be modified (replace spring configuration). I am not entirely sure where the BC Racing BR coilovers stand in that regard, but unless the configuration replicates that of JRZ or MCS, you'll likely need a minimum of 5mm spacers as you mentioned.

Of course, front tire size and model will heavily contribute to both inside clearance to the suspension and outside clearance to the fender edge.

18x11" Rear Fitment Notes:

The ideal offset for accommodating 305/35-18 tires like the models mentioned at the beginning of the post on an 18x11" wheel is around ET28-29. Note at full droop the wheel/tire will typically make light contact with the subframe, so you'll need to ensure you are securing the wheel to the hub evenly. Once under load, there is plenty of clearance (see pictures below). Negative camber and fender rolling is required to prevent rubbing under suspension compression.

Here are a couple of photos of my E92 M3 which is running a similar setup - 275/35-18 / 305/35-18 NT01. As a side note, I strongly prefer piloting my car with my other 18x10.5" rotatable square setup. I was also about ~3 seconds faster when I compared the two configurations back to back during my last outing at Thunderhill, so that reinforced the butt dyno.





Subframe contact under full droop 305/35-18 NT01's:



Clearance under load:



- Ryan

[Agetec]

Originally Posted by ApexRaceParts

Is this a setup for street use, or will it see track time?

If your goal is to run 305/35-18 out back, then 275/35-18 would be the best match for the front. The two popular tire choices that I am aware of in those sizes are the Nitto NT01 and Toyo R888R, and we strongly prefer the NT01 for track use. I am not familiar with any street tires that are offered in these sizes.

18x10.5" Front Fitment Notes:

Fitting 18x10.5" wheels under the front fender arches is a balancing act between the following:

• Selecting wheels with an appropriate offset
• Dialing in the appropriate amount of negative camber
• Taking into consideration the intended tire size and model (not all are created equal)
• Taking into consideration your existing or future suspension silhouette and spring stack height

Even with all of the above dialed in, enthusiasts considering 10.5" wheels with a track-oriented compound should expect some light scrubbing around the liners under suspension compression or at steering angle - Par for the course for fast lap times.

The ideal offset for a 10.5" wheel on the front of an E9X M3 is typically between ET17 and ET22. The higher the offset within that range, the less negative camber you are forced to run to clear the fender arches. Most hardcore track guys running 10.5" wheels up front are already running somewhere around -3.5º, so dialing in negative camber shouldn't really be a barrier. We chose to produce our 10.5" wheels for the E9X M3 chassis with an offset of ET22, and since many will run these wheels in the rear as a part of a rotatable square setup or as a staggered setup, anything lower than an ET22 would limit rear tire width due to rubbing the rear fenders.

Beyond using the correct wheel offset, the silhouette and stack height of the suspension is equally important. Motorsport oriented coilovers like JRZ and MCS with 5" linear springs work very well, and depending on the stack height helpers springs may or may not be used. The idea is to keep the lower spring perch above the tire where it does not impede clearance. With a suspension setup like this and approx. -3.5º of camber, 18x10.5" ET22 (or lower) can accommodate 295/30-18 compounds without spacers under the front fenders.

Other popular coilovers like KW and Ohlins R&T are known for eating up inner clearance, and will require spacers or will need to be modified (replace spring configuration). I am not entirely sure where the BC Racing BR coilovers stand in that regard, but unless the configuration replicates that of JRZ or MCS, you'll likely need a minimum of 5mm spacers as you mentioned.

Of course, front tire size and model will heavily contribute to both inside clearance to the suspension and outside clearance to the fender edge.

18x11" Rear Fitment Notes:

The ideal offset for accommodating 305/35-18 tires like the models mentioned at the beginning of the post on an 18x11" wheel is around ET28-29. Note at full droop the wheel/tire will typically make light contact with the subframe, so you'll need to ensure you are securing the wheel to the hub evenly. Once under load, there is plenty of clearance (see pictures below). Negative camber and fender rolling is required to prevent rubbing under suspension compression.

Here are a couple of photos of my E92 M3 which is running a similar setup - 275/35-18 / 305/35-18 NT01. As a side note, I strongly prefer piloting my car with my other 18x10.5" rotatable square setup. I was also about ~3 seconds faster when I compared the two configurations back to back during my last outing at Thunderhill, so that reinforced the butt dyno.

- Ryan

Thanks for replying to this post with the wealth of information i really appreciate it. Honestly been so busy with COVID-19 stuff forgot I posted this Thanks for all of yous guys input! I plan to do some occasional track runs with this car it's not a dedicated track platform "yet" it will spend alot of time on the street.