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[CravingBavaria]

I have a set of 18x10 +25 squared RIA's on the way - 275/35x18 tires - Ohlins RT's coils. I'm hoping this is common enough that someone can suggest what spacers to run for very flush fitment? I've heard 5mm front should be good, but not sure what the back will need. TIA!

[bipp]

5mm front 12mm rear.

This also depends somewhat on your camber settings. I run 18x10.5 ET22 RI-A up front with a 5mm (same wheel, no spacer rear but could add a 5mm for fitment) for strut clearance on 275/35/18 CRS (so effectively 15mm for you) at -3 camber front and it seems flush. With a wider section width tire such as the Continental ECF the sidewall pokes a little. At large compression events, at Laguna T6 and T8a, I rub the tire sidewall somewhat but this is unavoidable due to the nature of the corner. It has never rubbed on the street.

https://www.m3post.com/forums/showthread.php?t=877719 for "flush" on 18x10 ET25 275/35/18.

[1FastSicilian]

I ran that same set up before.. If you look through my journal you'll see pictures of my old 18x10 sq TEs (ones with stickers) and I did 5mm front and 10mm rear but my car sits pretty low.

[CravingBavaria]

Thanks gents! Exactly what I was looking for. Sounds like both 10mm or 12mm would work. Will probably get both and play around with

[bipp]

Originally Posted by CravingBavaria

Thanks gents! Exactly what I was looking for. Sounds like both 10mm or 12mm would work. Will probably get both and play around with

Can't go wrong with either. I used to run 10mm spacers in the rear with 19x10 ET25 ZCP wheels.

Might want to note that 12mm spacers are hubcentric and thus are a bit safer. See this post for more details: https://www.m3post.com/forums/showpo...63&postcount=6

With this in mind, I've run the 10mm spacer and also tracked the car without problem. Just figured it was worth raising for your awareness.

[M3SQRD]

Originally Posted by bipp

5mm front 12mm rear.

This also depends somewhat on your camber settings. I run 18x10.5 ET22 RI-A up front with a 5mm (same wheel, no spacer rear but could add a 5mm for fitment) for strut clearance on 275/35/18 CRS (so effectively 15mm for you) at -3 camber front and it seems flush. With a wider section width tire such as the Continental ECF the sidewall pokes a little. At large compression events, at Laguna T6 and T8a, I rub the tire sidewall somewhat but this is unavoidable due to the nature of the corner. It has never rubbed on the street.

https://www.m3post.com/forums/showthread.php?t=877719 for "flush" on 18x10 ET25 275/35/18.

Where did the effective 15 mm come from? Using your 10.5et17, a 10et25 would match your frontspacing if the wheel specs were 10et13.

If I’m reading the above thread correctly, he used a 12 mm front spacer with NT01 to clear the strut. A 10et25 with a 12 mm thick spacer is 10et13 which matches your 10.5et17. Where’s the “flush” fitment in the linked thread?

[bipp]

Originally Posted by M3SQRD

Where did the effective 15 mm come from? Using your 10.5et17, a 10et25 would match your frontspacing if the wheel specs were 10et13.

If I’m reading the above thread correctly, he used a 12 mm front spacer with NT01 to clear the strut. A 10et25 with a 12 mm thick spacer is 10et13 which matches your 10.5et17. Where’s the “flush” fitment in the linked thread?

10.5 ET22 with 5mm == 10 ET25 with 15mm as far as where the outer edge of the wheel sits for visual reference to the fender. I used this (https://jr-wheels.com/et-calculator) to check - maybe the tool is wrong. I'

The "flush" fitment I'm referring to is in the first post. It seems like he did 5mm F / 12mm R with 10 ET25 for a "flush" visually fitment with PSS. I'm not sure if the 5mm spacer was for strut clearance which might be needed with KW/Ohlins.

KW Clubsport Coilovers
Apex EC-7 18x10 et25 (square)
Michelin PSS 275/35/18 (square)
Apex 12mm spacer rear
Apex 5mm spacer front

[M3SQRD]

Looks like we were both wrong…10et11 is the closest match.

10” frontspacings:
11 / 2 - 11 / 25.4 = 5.0669”
Delta = 5.0669 - 5.0807 = -0.0138”

11 / 2 - 10 / 25.4 = 5.106”
Delta = 5.106 - 5.0807 = 0.0253”

Your frontspacing:
11.5 / 2 - (22 - 5) / 25.4 = 5.0807”

I have no idea how they got 4.915”?

An offset of 15 is the closet to their incorrect 4.915”:
11 / 2 - 15 / 25.4 = 4.909”
Delta 4.909 - 4.915 = -0.006”

Don’t blindly trust online calculators.

[bipp]

Originally Posted by M3SQRD

Looks like we were both wrong…10et11 is the closest match.

10” frontspacings:
11 / 2 - 11 / 25.4 = 5.0669”
Delta = 5.0669 - 5.0807 = -0.0138”

11 / 2 - 10 / 25.4 = 5.106”
Delta = 5.106 - 5.0807 = 0.0253”

Your frontspacing:
11.5 / 2 - (22 - 5) / 25.4 = 5.0807”

I have no idea how they got 4.915”?

An offset of 15 is the closet to their incorrect 4.915”:
11 / 2 - 15 / 25.4 = 4.909”
Delta 4.909 - 4.915 = -0.006”

Don’t blindly trust online calculators.

Hmm, guessing their math is off due to not adding the 1inch from flange. Figured I'd check it since it seemed like a likely cause of their error.

10.5/2 - (22-5)/25.4 = 4.58ish
10/2 - (25-15)/25.4 = 4.6ish

Good call. Probably shouldn't trust that site anymore... and probably just calculate it myself moving forward.

[M3SQRD]

Originally Posted by bipp

Hmm, guessing their math is off due to not adding the 1inch from flange. Figured I'd check it since it seemed like a likely cause of their error.

10.5/2 - (22-5)/25.4 = 4.58ish
10/2 - (25-15)/25.4 = 4.6ish

Good call. Probably shouldn't trust that site anymore... and probably just calculate it myself moving forward.

Even using the wheel width doesn’t explain it.

10.5 / 2 - (22 - 5) / 25.4 = 4.581” vs. 4.951” (their calculated 10.5et22 frontspacing)

If the inner wheel width of 10.5”, instead of 11.5” outer wheel width, was used there would be exactly a 0.5” difference between the two frontspacings. Difference 4.951 - 4.581 = 0.37”. If you use an outer wheel width of 11.75” (?!?!) then you get a frontspacing of 4.95” (using only two decimal places) which matches their website’s calculated frontspacing of 4.95”. Where the hell did they find, or did they determine on their own, that a wheel outer width is 0.75” wider than a wheel inner width? As an engineer, I can’t stand not knowing how someone can screwup such a simple calculation (coworkers did not like it when I was asked to review their work) so I had to figure it out

[bipp]

Originally Posted by M3SQRD

Even using the wheel width doesn’t explain it.

10.5 / 2 - (22 - 5) / 25.4 = 4.581” vs. 4.951” (their calculated 10.5et22 frontspacing)

If the inner wheel width of 10.5”, instead of 11.5” outer wheel width, was used there would be exactly a 0.5” difference between the two frontspacings. Difference 4.951 - 4.581 = 0.37”. If you use an outer wheel width of 11.75” (?!?!) then you get a frontspacing of 4.95” (using only two decimal places) which matches their website’s calculated frontspacing of 4.95”. Where the hell did they find, or did they determine on their own, that a wheel outer width is 0.75” wider than a wheel inner width? As an engineer, I can’t stand not knowing how someone can screwup such a simple calculation (coworkers did not like it when I was asked to review their work) so I had to figure it out

Hah, it's always fun to root-cause someone else's mistake :P

[CravingBavaria]

Originally Posted by bipp

Can't go wrong with either. I used to run 10mm spacers in the rear with 19x10 ET25 ZCP wheels.

Might want to note that 12mm spacers are hubcentric and thus are a bit safer. See this post for more details: https://www.m3post.com/forums/showpo...63&postcount=6

With this in mind, I've run the 10mm spacer and also tracked the car without problem. Just figured it was worth raising for your awareness.

I was looking into Turner spacers and the description for both of their 10mm and 12.5mm (they don't have 12mm) say that both options are hubcentric. Is this possible? I don't know enough about this, but assumed it was the length that mattered and couldn't be fixed with a different design.

[bipp]

Originally Posted by CravingBavaria

I was looking into Turner spacers and the description for both of their 10mm and 12.5mm (they don't have 12mm) say that both options are hubcentric. Is this possible? I don't know enough about this, but assumed it was the length that mattered and couldn't be fixed with a different design.

I notice this on their site:

ECS spacers:

***In some cases, the OEM hub flange extends farther than the thickness of the spacer. This creates a need for a larger chamfer on the spacer for adequate wall thickness. ECS's 10mm spacer is designed to be compatible with OEM wheels; however, in some instances, it is incompatible with certain aftermarket wheel options. A simple fix is to switch to either an 8mm or 12.5mm spacer.***

Turner spacers:

10mm Fitment Note: You must be very careful when fitting 10mm spacers to any BMW. Since the depth of the hubcentric lip will vary, you risk bottoming out of the spacer before it sits flush with the hub. This will leave a gap between the spacer and the hub, seriously compromising the strength of the spacer. The lip on the car may need to be shaved down so the 10mm spacer will fit flush on the rotor hat.

I guess it's a try it for yourself thing - I didn't have a problem with 10mm Macht Schnell spacers before on OEM wheels but I don't think I can say for sure that you won't have problems.

[CravingBavaria]

Originally Posted by bipp

I notice this on their site:

ECS spacers:


Turner spacers:


I guess it's a try it for yourself thing - I didn't have a problem with 10mm Macht Schnell spacers before on OEM wheels but I don't think I can say for sure that you won't have problems.

Thanks for checking that. I would assume based on the ECS note about switching to an 8mm or 12.5mm that Turner's 12.5mm would be a safer choice than their 10mm. I will go with that. Appreciate the help!

[kaiv]

I'm running the same setup with 10mm spacers rear, none front. Looks great.
You could probably go 5F, 15R to be extra flush but it also depends on camber.

[M3SQRD]

Originally Posted by bipp

I notice this on their site:

ECS spacers:


Turner spacers:


I guess it's a try it for yourself thing - I didn't have a problem with 10mm Macht Schnell spacers before on OEM wheels but I don't think I can say for sure that you won't have problems.

This problem applies to all 10 mm spacers regardless of the manufacturer (I had an issue with a Macht Schnell spacer on my ‘09 e92 M3). The hub centering ring height has a ~0.5 mm tolerance so it’s typically between 9.0-9.5 mm. You’ll start to run into problems at 9.5 mm with a 10 mm spacer. It is not something you can visually see. Always check with a sheet of paper to see if it will slip between the brake rotor mounting face and the bottom of the spacer. There’s a problem if the sheet of paper slides in between them. However, you can grind down the height of the ring if the 10 mm spacer is bottoming out.

[CravingBavaria]

Originally Posted by kaiv

I'm running the same setup with 10mm spacers rear, none front. Looks great.
You could probably go 5F, 15R to be extra flush but it also depends on camber.

Kaiv! I'll have to swing by your shop sometime. I ended up going with 12.5R 5F and it's perfect, no rubbing with about -2.7deg camber F&R. I'll post some pics in this thread soon.