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      10-13-2020, 10:20 AM   #1
BRMF82
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Wheels to suit 27/65-18 Michelin Slicks?

Does anyone know what size rim that would fit an M4 and suit 27/65-18 Michelin Slicks? Has to be that size, its Cup Car front (an abundance of them being unused.)

Michelin tech data says it suits an 11" wheel, rim width range 9.5-11.5

Ideally running bilstein Clubsports and no body modifications - Square setup only so I can use them on all corners.

If it could also run a cup2 size that would be great, sizes available in Australia are 265/35/18 or 295/30/18.

Ideally something cost effective yet strong (track only wheel)

Thanks!
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      10-13-2020, 11:35 AM   #2
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I run 18x11 square with a 25mm spacer up front using Apex EC-7 18x11 +44 wheels. 295/30r18 Toyo RR clears the strut, fender, and liner without rubbing/contact. If the dimensions of that slick are close to the RR, buy one wheel/tire and check for fitment front and rear.
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      10-13-2020, 02:55 PM   #3
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Fitment

Forgeline GTD1 Square 18x10 Et 27 Pirelli 285/645/18.
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      10-13-2020, 05:10 PM   #4
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Quote:
Originally Posted by jacobe92 View Post
Forgeline GTD1 Square 18x10 Et 27 Pirelli 285/645/18.
How much space do you have for the strut and guard? It's my understanding that pirelli make quite a small sick
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      10-13-2020, 09:19 PM   #5
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Originally Posted by jacobe92 View Post
Forgeline GTD1 Square 18x10 Et 27 Pirelli 285/645/18.
Nice! Where do you buy yours from?
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      10-13-2020, 10:42 PM   #6
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When I last checked (around 2-3 years ago?), the Porsche GT3 Carrera/Cup cars had the Michelin N2# 27/65/18 slick fitted to a custom sized 18x10.25" (286mm wide) wheel.
The section width of one of these brand new Michelin slicks fitted to this custom wheel was 290mm and the OD was 645mm.
At that time, based on the Michelin's advertised section width of 298mm on a measured 11" wheel, the section width should have been 290.5mm on the 10.25" wide wheel (i.e. 5mm less section width for each 0.5" reduction in wheel width), which is more or less exactly what it was.
Note: the Michelin-published 298mm section width was from 2015. The latest Michelin catalogs specify it as 295mm.

I fitted one of these used slicks to an 18x9 and 18x10 wheel to get some further section widths and ODs for fitment data:
  • 18x9, 266mm, 651mm OD - should have been 278mm/9" - actual is 12mm less!!!
  • 18x10, 281mm, 647mm OD - should have been 288mm/10" - actual is 7mm less!!!
And calculated values based on 9" and 10" measurements:
  • 18x9.5, ~274mm, ~649mm OD - should have been 283mm/9.5" - actual is ~9mm less!!!
And the custom wheel:
  • 18x10.25" 290mm, 645mm OD - should have been 290.5mm/10.25" - actual is exact!
So, either, the used slick had shrunk and its section width was less than expected on narrower wheels, OR, the slick is substantially narrower when fitted to much narrower wheels relative to the 11" measured wheel.

I've seen various dedicated M3 track cars on this forum use 18x10.5 et22 with wide slicks (for which the N2# would have ~293mm section width based on 2015 data, or ~290mm based on the 2020 data) but you'd be better off taking your own measurements to confirm fitment on your car.
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      10-13-2020, 10:45 PM   #7
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Quote:
Originally Posted by 135 View Post
When I last checked (around 2-3 years ago?), the Porsche GT3 Carrera/Cup cars had the Michelin N2# 27/65/18 slick fitted to a custom sized 18x10.25" (286mm wide) wheel.
The section width of one of these brand new Michelin slicks fitted to this custom wheel was 290mm and the OD was 645mm.
Based on the Michelin's advertised section width of 298mm on a measured 11" wheel, the section width should have been 290.5mm on the 10.25" wide wheel (i.e. 5mm less section width for each 0.5" reduction in wheel width), which is more or less exactly what it was.
Note: the Michelin-published 298mm section width was from 2015. The latest Michelin catalogs specify it as 295mm.

I fitted one of these used slicks to an 18x9 and 18x10 wheel to get some further section widths and ODs for fitment data:
  • 18x9, 266mm, 651mm OD - should have been 278mm/9" - actual is 12mm less!!!
  • 18x10, 281mm, 647mm OD - should have been 288mm/10" - actual is 7mm less!!!
And calculated values based on 9" and 10" measurements:
  • 18x9.5, ~274mm, ~649mm OD - should have been 283mm/9.5" - actual is ~9mm less!!!
And the custom wheel:
  • 18x10.25" 290mm, 645mm OD - should have been 290.5mm/10.25" - actual is exact!!!
So, either, the used slick had shrunk and its section width was less than expected on narrower wheels, OR, the slick is substantially narrower when fitted to much narrower wheels relative to the 11" measured wheel.

I've seen various dedicated M3 track cars on this forum use 18x10.5 et22 with wide slicks (for which the N2# would have ~293mm section width based on 2015 data, or ~290mm based on the 2020 data) but you'd be better off taking your own measurements to confirm fitment on your car.
Hugely appreciated! Thank you very much.
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      10-13-2020, 10:51 PM   #8
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No problem at all.

Also, rather than importing wheels, have a look at Koya wheels as a local option. They provide semi-forged and forged wheels to a number of race teams and track cars and have several styles in 18" - the forged wheels can be custom made in any design.
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      10-14-2020, 12:54 AM   #9
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Quote:
Originally Posted by gum2012 View Post
Quote:
Originally Posted by jacobe92 View Post
Forgeline GTD1 Square 18x10 Et 27 Pirelli 285/645/18.
Nice! Where do you buy yours from?
I bought mine directly from Forgeline.
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      10-14-2020, 12:57 AM   #10
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Quote:
Originally Posted by BRMF82 View Post
Quote:
Originally Posted by jacobe92 View Post
Forgeline GTD1 Square 18x10 Et 27 Pirelli 285/645/18.
How much space do you have for the strut and guard? It's my understanding that pirelli make quite a small sick
It didn't clear the front. I had to put a 5mm spacer to clear it. Rear was good.
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      11-14-2020, 08:42 PM   #11
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Quote:
Originally Posted by 135 View Post
...
I fitted one of these used slicks to an 18x9 and 18x10 wheel to get some further section widths and ODs for fitment data:
  • 18x9, 266mm, 651mm OD - should have been 278mm/9" - actual is 12mm less!!!
  • 18x10, 281mm, 647mm OD - should have been 288mm/10" - actual is 7mm less!!!
And calculated values based on 9" and 10" measurements:
  • 18x9.5, ~274mm, ~649mm OD - should have been 283mm/9.5" - actual is ~9mm less!!!

So, either, the used slick had shrunk and its section width was less than expected on narrower wheels, OR, the slick is substantially narrower when fitted to much narrower wheels relative to the 11" measured wheel.
An update to my post above...

I have just fitted some Michelin N2# 27/65/18 scrubs to 9.5" and 10" wide wheels.

The 10" fitment resulted in the same 281mm section width. The sidewalls are practically flush with the wheel's flange.
A 10" wide wheel is measured to the bead seats inside the wheel's flanges and the wheel is actually ~11" (279mm) wide to the outside of the flanges, which is what is measured to and what can potentially contact on suspension, or bodywork, if the tyre is undersized/stretched for the wheel - see my previous post for more discussion on this topic).

The 9.5" fitment resulted in a 273mm section width, which is only a minimal 1mm difference to my previously calculated value (based on the section widths of scrubs fitted to 9" and 10" wide wheels).
Actually, I rounded up my previous calculated value of 273.5mm to 274mm, so there really wasn't anything in it between the actual and calculated values.

So these are the second set of Michelin N2# scrubs that measure less than expected based on Michelin's advertised section width (both 2015 and 2017-2020).

The tread width of the Michelin N2# 27/65/18 is 252mm (2015) or 263mm (2017-2020), which seems quite narrow for such a wide section width (298mm in 2015, 295mm in 2017-2020) but, while it might be more commonplace with slicks, is more reasonable when in context of fitment to 9.5" and 10" wide wheels, tending to a more square-shouldered tyre, particular on a 9.5" wide wheel.
Interestingly, the tread width was 270mm in 2008 and 274mm in 2013, so it looks like Michelin has changed the specification on their slicks, as they would have through development over the years.

Note, Michelin (2019,2020) states the nominal wheel width for the N2# 27/65/18 is 11" +/-0.5".

Also, these scrubs weighed 9.8 kg (21.6 lbs).
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      11-25-2020, 08:34 AM   #12
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I have a set of scrubs in these sizes going on..in SL9 compound...on a 10” square wheel set.
For those with experience....how much camber do they like ? What hot pressures ?
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      11-25-2020, 09:59 AM   #13
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The Michelin catalogue specifies various ranges for combinations of camber, minimum hot pressures and number of stints (races). It doesn't differentiate between front and rear.

Broadly speaking, camber -2° to -4° and min hot 29-33psi.

See page 52 for details to determine the minimum hot pressure for your target camber. Most likely the second table - the first table is specifically for TCR.

http://pneu-sport.cz/download/catalo...in-circuit.pdf
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      11-25-2020, 10:15 AM   #14
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Quote:
Originally Posted by 135 View Post
The Michelin catalogue specifies various ranges for combinations of camber, minimum hot pressures and number of stints (races). It doesn't differentiate between front and rear.

Broadly speaking, camber -2° to -4° and min hot 29-33psi.

See page 52 for details to determine the minimum hot pressure for your target camber. Most likely the second table - the first table is specifically for TCR.

http://pneu-sport.cz/download/catalo...in-circuit.pdf
Thank You !
Not sure tho how to interpret the 0, 1, and 2 values shown in the “mini hot pressures” table. That may take some research. Any insights ?
.

Last edited by M2C AW; 11-25-2020 at 10:40 AM..
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      11-26-2020, 02:14 AM   #15
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The 0/1/2 numbers refer the number of stints (races), at the specified race length (e.g. 180 km), that can be performed on one set of tyres at the specified camber/pressure combination.

If your sessions are 10 laps at 2.5 km per lap, then you're only doing 25 km sessions, quite some way off the 180 km sessions/races they are designed for.
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      11-26-2020, 10:51 AM   #16
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Out of curiosity, where do people get the MICHELIN scrubs from?
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      11-26-2020, 03:25 PM   #17
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Quote:
Originally Posted by Gomeler View Post
I run 18x11 square with a 25mm spacer up front using Apex EC-7 18x11 +44 wheels. 295/30r18 Toyo RR clears the strut, fender, and liner without rubbing/contact. If the dimensions of that slick are close to the RR, buy one wheel/tire and check for fitment front and rear.
Curious where are you sourced the studs (105mm?) and 25mm spacers?
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      11-27-2020, 05:49 AM   #18
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Quote:
Originally Posted by CRRobert View Post
Out of curiosity, where do people get the MICHELIN scrubs from?
Being in the USA, you could try https://usedracingtires.com
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      12-02-2020, 05:27 PM   #19
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Quote:
Originally Posted by CRRobert View Post
Out of curiosity, where do people get the MICHELIN scrubs from?
I get all my used slicks from local race teams I have connections with but there's a few online resellers out there too.
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      12-04-2020, 10:58 AM   #20
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Quote:
Originally Posted by fanatic1 View Post
Curious where are you sourced the studs (105mm?) and 25mm spacers?
H&R bolt-on spacers, OEM lug bolts clamping the tire to the spacer. Spacer came with bolts to secure it to the hub.
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      12-04-2020, 01:56 PM   #21
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Quote:
Originally Posted by Gomeler View Post
H&R bolt-on spacers, OEM lug bolts clamping the tire to the spacer. Spacer came with bolts to secure it to the hub.
Saw those and wondered if they were safe for track use, but sounds like you’ve use them with no issue
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