28.5” OD vs 27” OD

Stelios619 · 04-08-2021, 04:45 AM

Picked up a set of 21” HRE P104’s, however, the fronts were built for an F10 M5, while the rears are offset for an F12 M6 (21x9.5 et27 and 21x11 et52). Which means I’d need a 7mm spacer to bring the offset to factory, or a 20mm spacer to bring it out to match the front offset. Which also means that I have some room to play with tire width/spacers.

Option A: Michelin 4s 305/25zr21 rear, 265/30zr21 front, which are 27” and 27.3” tall, respectively. This is also the height of the factory tires on 20” wheels. For this setup I’d purchase the Future Classic 18MM spacer kit.

Option B: Michelin Sport Cup 2 315/30zr21 rear, 275/35zr21 front, which are both 28.5” tall. For this, I’m thinking the Future Classic 10MM kit (?).

The obvious disadvantage to taller tires is that my speedometer will be out of wack by 5-6%. But, I’m wondering how it may look, and if the taller tires will even fit in the front.

Not that the roads that I generally travel on are bad, but I do kinda like the idea of more sidewall on a 21” wheel.

Do I *need* a Cup 2? Not at all. 99% of my driving is highway (being in the country, speeds of 100+ for a handful of miles at a time are incredibly common). But I’m just sort of curious about the sizing, and it might give me an opportunity to try the tire should I ever feel like tracking the car (I live 10 minutes away from my local track).

Thanks guys.

brad850csi · 04-16-2021, 12:34 AM

52 offset at the rear? Are you sure?

I do think the tyres will be a bit too tall as well.

atillathetom · 04-21-2021, 10:29 AM

11et52 was not built for an F06/12/13 M6. That would be 27MM retracted on the outside compared to the stock 343M. Most wheels made for the M6 would be another 12mm or so more aggressive...something like 11et13 to be flush on the M6 at which point you would have issues on the rear of the M5. Can you confirm the rear offset?

Stelios619 · 04-21-2021, 10:36 PM

Quote:

Originally Posted by atillathetom

11et52 was not built for an F06/12/13 M6. That would be 27MM retracted on the outside compared to the stock 343M. Most wheels made for the M6 would be another 12mm or so more aggressive...something like 11et13 to be flush on the M6 at which point you would have issues on the rear of the M5. Can you confirm the rear offset?

Sorry, it was actually made for a 640i, according to HRE (via email and serial number tracking).

04-08-2021, 04:45 AM	#1
Stelios619 Private First Class 20 Rep 110 Posts Drives: BMW M3 Join Date: Jun 2020 Location: SLC, UT iTrader: (0)	28.5” OD vs 27” OD Picked up a set of 21” HRE P104’s, however, the fronts were built for an F10 M5, while the rears are offset for an F12 M6 (21x9.5 et27 and 21x11 et52). Which means I’d need a 7mm spacer to bring the offset to factory, or a 20mm spacer to bring it out to match the front offset. Which also means that I have some room to play with tire width/spacers. Option A: Michelin 4s 305/25zr21 rear, 265/30zr21 front, which are 27” and 27.3” tall, respectively. This is also the height of the factory tires on 20” wheels. For this setup I’d purchase the Future Classic 18MM spacer kit. Option B: Michelin Sport Cup 2 315/30zr21 rear, 275/35zr21 front, which are both 28.5” tall. For this, I’m thinking the Future Classic 10MM kit (?). The obvious disadvantage to taller tires is that my speedometer will be out of wack by 5-6%. But, I’m wondering how it may look, and if the taller tires will even fit in the front. Not that the roads that I generally travel on are bad, but I do kinda like the idea of more sidewall on a 21” wheel. Do I need a Cup 2? Not at all. 99% of my driving is highway (being in the country, speeds of 100+ for a handful of miles at a time are incredibly common). But I’m just sort of curious about the sizing, and it might give me an opportunity to try the tire should I ever feel like tracking the car (I live 10 minutes away from my local track). Thanks guys.
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04-16-2021, 12:34 AM	#2
brad850csi Colonel 1316 Rep 2,349 Posts Drives: 16 F13 M6 Comp Join Date: Jan 2015 Location: Auckland, New Zealand iTrader: (0)	52 offset at the rear? Are you sure? I do think the tyres will be a bit too tall as well. __________________ SCOTT26 "So as an admirer of the M5 and a potential customer of an M5 Touring. I would run naked around the streets of Garching if they were to offer one."
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04-21-2021, 10:29 AM	#3
atillathetom Lieutenant 65 Rep 531 Posts Drives: Bike Join Date: Jun 2008 Location: San Diego iTrader: (0)	11et52 was not built for an F06/12/13 M6. That would be 27MM retracted on the outside compared to the stock 343M. Most wheels made for the M6 would be another 12mm or so more aggressive...something like 11et13 to be flush on the M6 at which point you would have issues on the rear of the M5. Can you confirm the rear offset?
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