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      12-21-2021, 08:28 PM   #1
8262S
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Why OEM spec 19” front and 20” rear on M3?

Hello. I just did paperwork for a reservation slot for an M3CX and am hoping for delivery around March.

I intend to buy winter tires over the summer to not run into the availability problem that some here are reporting. Sucks to hear some of you are running into supply problems.

In researching tires, I read somewhere that the front tires was 19” to put more weight on the front tire, but can’t recall the source. Is that true? If not, why is it OEM 19” front and 20” rear?

I ask because I’m looking for a second set of wheels and am trying to figure out if I need to follow that OEM 19”/20” sizing.

I am on the fence of keeping the OEM wheels as summer wheels and getting a less expensive pair of winter wheels. Then the question is what size.

Alternately am debating using the OEM wheels for winter and getting a set of M Performance Frozen Gold Matt 1000 M wheels (20/21" Front/Rear) for summer. They would look incredible on a Dravit Grey M3. But when I looked for those wheels in the BMW individual configuration site it listed the sizes as 20”/21”.

I am happy with 19/20, 20/20, 20/21. Not sure I have a strong preference but know that I want to use the Michelin Pilot *BMW OEM spec tires long term as my summer tire.

I would like to understand why the tires are 19/20, versus 20/20, so I can intelligently make a decision. “It just looks cool” is probably not what the BMW engineers said. LOL. I watched the *BMW video and was amazed at how many tires they tested before arriving at the OEM spec. I would bet they out the same amount of work into wheel size.

And I did do a forum search but didn’t find any helpful threads. Sorry if I missed something relevant.

Thanks.

PS This was originally erroneously posted in the F80 forum. Sorry 'bout that....
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      12-21-2021, 08:42 PM   #2
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From a quick search, I found this thread:

https://g80.bimmerpost.com/forums/sh....php?t=1788420

Seems to be a good start to the discussion.

Many (most?) of us running snow tire set-ups for winter, are running the front 19x9.5 (with 275/35 19 tires) all around.

I suspect that the more G8x cars get tracked, the more we'll start seeing square 19 (and even square 18) set-ups for track duty.

I've also seen some folks running square 20s, and the 21/20 staggered set-up you mention above. The bigger rims look great, although I happen to think a chunky sidewall (35 or even 40 aspect ratio) looks good too, with the right wheel.
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      12-21-2021, 09:12 PM   #3
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Quote:
Originally Posted by HorsePower View Post
From a quick search, I found this thread:

https://g80.bimmerpost.com/forums/sh....php?t=1788420

Seems to be a good start to the discussion.

Many (most?) of us running snow tire set-ups for winter, are running the front 19x9.5 (with 275/35 19 tires) all around.

I suspect that the more G8x cars get tracked, the more we'll start seeing square 19 (and even square 18) set-ups for track duty.

I've also seen some folks running square 20s, and the 21/20 staggered set-up you mention above. The bigger rims look great, although I happen to think a chunky sidewall (35 or even 40 aspect ratio) looks good too, with the right wheel.
Thanks! You've given me something to do the rest of the night.

I feel like I am going to know so much about this M3 when I get it, but I'm sure it will just be the starting point.

EDIT: I read that thread, thanks for the link! It does answer the question. Case closed it seems for OEM 19/20. But for winter tires the sheer pucker factor of turn in might not matter as much (i.e., 19/19 or even 18/18 for larger sidewall). I have been using Michelin Xi3 tires for the past several winters on my WRX and they are definitely not a precise turning tire, and I tend to baby them to not burn them up on dry pavement.

Last edited by 8262S; 12-21-2021 at 10:49 PM..
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      12-22-2021, 10:59 AM   #4
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Quote:
Originally Posted by 8262S View Post
Thanks! You've given me something to do the rest of the night.

I feel like I am going to know so much about this M3 when I get it, but I'm sure it will just be the starting point.

EDIT: I read that thread, thanks for the link! It does answer the question. Case closed it seems for OEM 19/20. But for winter tires the sheer pucker factor of turn in might not matter as much (i.e., 19/19 or even 18/18 for larger sidewall). I have been using Michelin Xi3 tires for the past several winters on my WRX and they are definitely not a precise turning tire, and I tend to baby them to not burn them up on dry pavement.
After a few hundred miles of G80 driving on a square set-up of 275/35 19 Wintrac Pro snow tires, I can say that even on very twisty, fun roads at a good pace, the square set-up feels great. I think at any safe and reasonable street speeds, 99.9% of drivers will not feel any appreciable handling difference on the G8x platform between 20/19 and 19 square, particularly when talking about snow tires (which aren't the most precise to begin with).

Funny you mention a Subie with Michelins. I ran PA4s on my '18 STi. They were a surprisingly good performance tire, and were pretty great for that car on packed snow and ice. But if I put them on too early in the season and caught a warm day, or left them on too late, warm dry pavement ate them up like candy.
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      12-22-2021, 11:19 AM   #5
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Originally Posted by HorsePower View Post
After a few hundred miles of G80 driving on a square set-up of 275/35 19 Wintrac Pro snow tires, I can say that even on very twisty, fun roads at a good pace, the square set-up feels great. I think at any safe and reasonable street speeds, 99.9% of drivers will not feel any appreciable handling difference on the G8x platform between 20/19 and 19 square, particularly when talking about snow tires (which aren't the most precise to begin with).

Funny you mention a Subie with Michelins. I ran PA4s on my '18 STi. They were a surprisingly good performance tire, and were pretty great for that car on packed snow and ice. But if I put them on too early in the season and caught a warm day, or left them on too late, warm dry pavement ate them up like candy.
2013 WRX here. I totally agree. Warm dry pavement and aggressive driving wears winter tires very fast. Once I put the snows on, I save my fun driving for when there is snow on the ground. Then they are an absolute blast!

And I do think I will consider even an 18” wheel for a higher profile tire (same OEM tire diameter). We can get some horrible potholes so if I can fit an 18” over the calibers I might go that route. Heck, I was even looking at inexpensive rally wheels. I do plan on using the M3 for ice time trial races, so won’t mind a rally look for the winter.

My WRX is sitting in the garage wearing Xi3’s and steelies, but I won’t do that to the M3. LOL
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      12-22-2021, 01:34 PM   #6
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Quote:
Originally Posted by 8262S View Post
2013 WRX here. I totally agree. Warm dry pavement and aggressive driving wears winter tires very fast. Once I put the snows on, I save my fun driving for when there is snow on the ground. Then they are an absolute blast!

And I do think I will consider even an 18” wheel for a higher profile tire (same OEM tire diameter). We can get some horrible potholes so if I can fit an 18” over the calibers I might go that route. Heck, I was even looking at inexpensive rally wheels. I do plan on using the M3 for ice time trial races, so won’t mind a rally look for the winter.

My WRX is sitting in the garage wearing Xi3’s and steelies, but I won’t do that to the M3. LOL
The base G8x cars without choosing any optional wheel, come on 19 rear 18 fronts. So a square 18 set-up should work (although plenty have asked the question before, I don't think I've seen anyone actually do it yet). If you end up putting a G8x car on square 18s, please make sure to let us all know!
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      12-22-2021, 02:15 PM   #7
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Quote:
Originally Posted by HorsePower View Post
The base G8x cars without choosing any optional wheel, come on 19 rear 18 fronts. So a square 18 set-up should work (although plenty have asked the question before, I don't think I've seen anyone actually do it yet). If you end up putting a G8x car on square 18s, please make sure to let us all know!
Wilco, but they would still be the same diameter tire as a lower profile 19.

I take it there is no issue with different tire size and the M3 AWD system? Must be bc they offer 19/20, but can people mount what they want without any drivetrain issues?

As a WRX owner that is a no go and is bad for the AWD system.
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      12-22-2021, 04:13 PM   #8
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Quote:
Originally Posted by 8262S View Post
Wilco, but they would still be the same diameter tire as a lower profile 19.

I take it there is no issue with different tire size and the M3 AWD system? Must be bc they offer 19/20, but can people mount what they want without any drivetrain issues?

As a WRX owner that is a no go and is bad for the AWD system.
My understanding is that there are absolutely potential issues messing with the tire sizes for the x-drive. Differences in the overall diameter/circumference/revs per mile of the tires - overall differences, differences side to side, and differences front and rear, can all cause issues. I believe there is an official BMW spec as to the max differences - I don't know what that spec is. Those issues aren't unique to Subaru's AWD system.

That is likely a large part of why many people chose to go with the BMW-recommended winter sizes (square 275/35 19, which is the package offered by BMW dealers on the 829M wheels).

If I had an x-drive (I don't), I would personally likely stick with BMW-approved sizes for the duration of the warranty.
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      12-22-2021, 07:14 PM   #9
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Quote:
Originally Posted by HorsePower View Post
My understanding is that there are absolutely potential issues messing with the tire sizes for the x-drive. Differences in the overall diameter/circumference/revs per mile of the tires - overall differences, differences side to side, and differences front and rear, can all cause issues. I believe there is an official BMW spec as to the max differences - I don't know what that spec is. Those issues aren't unique to Subaru's AWD system.

That is likely a large part of why many people chose to go with the BMW-recommended winter sizes (square 275/35 19, which is the package offered by BMW dealers on the 829M wheels).

If I had an x-drive (I don't), I would personally likely stick with BMW-approved sizes for the duration of the warranty.
Thanks for the suggestion, I am going to stick with the BMW recommended spec as well. And the 829M's look pretty good and aren't too expensive.
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      12-23-2021, 07:17 AM   #10
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Originally Posted by 8262S View Post
Thanks for the suggestion, I am going to stick with the BMW recommended spec as well. And the 829M's look pretty good and aren't too expensive.
Sounds good. Just to make sure you know, the 829Ms are a cast wheel, not forged like the OEM wheels that come on G8x cars. Sometimes people can score a great deal on the 829M set, but if paying close to MSRP for them, many of us have decided to go aftermarket for the winter wheels (to save $1,000+ on the set), since the 829Ms are cast anyway. VMR, for example, offers many flow formed wheels (not forged, but not basic cast either) for hundreds less than the 829Ms. Other go-to forum brands for flow formed wheels (such as Apex) will also likely soon be coming out with G8x fitments. Getting set up for this winter was tough for many of us - by next winter, there should be more options available (and hopefully less of a tire shortage).

Another interesting option people have done, is to purchase 2 additional matching OEM front wheels, to make a square set of those (since you already get 2 with the car). Some of them are surprisingly affordable compared to what you think - including the jet black 826M 19 inch fronts.

The various OEM wheel options have widely varying pricing as "parts" even though they are all similarly priced as options (I believe my upcharge to go to 826Ms in jet black was $1,300 if I recall correctly).
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      12-23-2021, 07:29 AM   #11
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The OEM winter set up is the 829M with Michelin Pilot Alpin 5.

I would highly recommend it if you will be driving in snow frequently but you could put winters or all seasons on the OEM 19/20 if you want

Here is mine on both. The 19/20 looks much better but the 829's are very good in the cold and wet and very comfortable, far less harsh over bumps
Attached Images
  
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      12-23-2021, 07:52 AM   #12
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Quote:
Originally Posted by HorsePower View Post
Sounds good. Just to make sure you know, the 829Ms are a cast wheel, not forged like the OEM wheels that come on G8x cars. Sometimes people can score a great deal on the 829M set, but if paying close to MSRP for them, many of us have decided to go aftermarket for the winter wheels (to save $1,000+ on the set), since the 829Ms are cast anyway. VMR, for example, offers many flow formed wheels (not forged, but not basic cast either) for hundreds less than the 829Ms. Other go-to forum brands for flow formed wheels (such as Apex) will also likely soon be coming out with G8x fitments. Getting set up for this winter was tough for many of us - by next winter, there should be more options available (and hopefully less of a tire shortage).

Another interesting option people have done, is to purchase 2 additional matching OEM front wheels, to make a square set of those (since you already get 2 with the car). Some of them are surprisingly affordable compared to what you think - including the jet black 826M 19 inch fronts.

The various OEM wheel options have widely varying pricing as "parts" even though they are all similarly priced as options (I believe my upcharge to go to 826Ms in jet black was $1,300 if I recall correctly).
Great info thanks! You are correct I do not need to pay a premium for a cast wheel with a BMW logo. And winter wheels can have a hard life depending on what you are doing with the car.

I think if I go the inexpensive wheel route, I’ll try to find something like a rally set that gives the car that look for the winter.

This forum has a lot of great information on it. Glad I found it!
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      12-23-2021, 07:59 AM   #13
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Quote:
Originally Posted by barryc365 View Post
The OEM winter set up is the 829M with Michelin Pilot Alpin 5.

I would highly recommend it if you will be driving in snow frequently but you could put winters or all seasons on the OEM 19/20 if you want

Here is mine on both. The 19/20 looks much better but the 829's are very good in the cold and wet and very comfortable, far less harsh over bumps
The 829M’s look good.

Is that car Dravit Grey?

I am considering putting snow tires on the 19/20 OEM’s and then getting a nice set of summer wheels, but that is the $$$$ option. I love how the matte gold 1000 M’s look but that would force me to 20/21. And if I still have another summer’s worth of tread left on my OEM 19/20 tires that might be a factor.

Like I said, I am not making a decision right now. I don’t even have a build date, and am cautiously waiting for BMW to delete more options based on chip and material shortages. LOL. I just want to do the research now so I can buy something this summer and avoid any shortages next October.

I am acutely aware of how bad summer tires are with even a dusting of snow. And this M3 will be my DD.
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      12-23-2021, 09:09 AM   #14
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Quote:
Originally Posted by 8262S View Post
Great info thanks! You are correct I do not need to pay a premium for a cast wheel with a BMW logo. And winter wheels can have a hard life depending on what you are doing with the car.

I think if I go the inexpensive wheel route, I’ll try to find something like a rally set that gives the car that look for the winter.

This forum has a lot of great information on it. Glad I found it!
Essentially everyone here is very welcoming and helpful. I was a LONG-time non-member reader (from way before the G8x days), and finally decided to join once my G80 was on the assembly line. Glad you are finding the forum helpful, and hopefully fun!
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      12-23-2021, 09:10 AM   #15
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Quote:
Originally Posted by barryc365 View Post
The OEM winter set up is the 829M with Michelin Pilot Alpin 5.

I would highly recommend it if you will be driving in snow frequently but you could put winters or all seasons on the OEM 19/20 if you want

Here is mine on both. The 19/20 looks much better but the 829's are very good in the cold and wet and very comfortable, far less harsh over bumps
Your car looks great. What did you use for lowering, and how do you like it?
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      12-23-2021, 09:17 AM   #16
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Quote:
Originally Posted by HorsePower View Post
Quote:
Originally Posted by barryc365 View Post
The OEM winter set up is the 829M with Michelin Pilot Alpin 5.

I would highly recommend it if you will be driving in snow frequently but you could put winters or all seasons on the OEM 19/20 if you want

Here is mine on both. The 19/20 looks much better but the 829's are very good in the cold and wet and very comfortable, far less harsh over bumps
Your car looks great. What did you use for lowering, and how do you like it?
Thanks, yes it is Dravit Gray

I have the MSS HAS kit. It's good quality and happy with it, but I wish it was a little lower in the front from the start but I've been told by a reliable source they will be sending out a retrofit kit to people who want to make the car a touch lower in the front. Car has spacers too.
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      12-23-2021, 10:11 AM   #17
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Quote:
Originally Posted by barryc365 View Post
Thanks, yes it is Dravit Gray

I have the MSS HAS kit. It's good quality and happy with it, but I wish it was a little lower in the front from the start but I've been told by a reliable source they will be sending out a retrofit kit to people who want to make the car a touch lower in the front. Car has spacers too.
Thanks for the info. Looks great. I wondered about the bit of additional wheel gap up front, compared to rear, on your car. That makes sense.

Enjoy!
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      01-16-2022, 10:22 PM   #18
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Quote:
Originally Posted by 8262S View Post
I take it there is no issue with different tire size and the M3 AWD system? Must be bc they offer 19/20, but can people mount what they want without any drivetrain issues?

As a WRX owner that is a no go and is bad for the AWD system.
Like all AWD systems, front to rear total diameter is absolutely a big deal. From what I've always been told, bmw is like Audi, and requires the f/r rolling diameter to be within 1% of each other. Just like you originally thought, you can do whatever combo you like, 19/21; 20/20, 20/21....whatever.

But make sure you keep the rolling diameters within 1%.

Last edited by bmw noob; 01-27-2022 at 10:42 PM..
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      01-17-2022, 08:28 AM   #19
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Yes, the tire diameter is absolutely essential with the AWD and it has to be within 1% front to rear.
What ppl often confuse is the fact, that the 19/20" combo is the closest possible to equal in terms of tire circumfense. The 275/35 19 is only marginally smaller than the 285/30 20". The 285/35 19" would already be too big. Just because the wheels are different diameters does not mean the tires are too.

If you drive a staggered setup, be sure to be in the 1% tolerance frame. Also the front tire must not be bigger in diameter than the rear. Smaller is fine. You can go for a 275/30 20" + 285/30 20" setup, or of course square 275 or 285, whatever you fancy.

I myself will put the PS4s* in 285/30 20" all around in my AWD M4.
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      01-17-2022, 09:40 AM   #20
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Thanks everyone.

I think I am just going to get the 19/20 826’s as my OEM summer wheel, and then get some 19’s for winter tires (undecided on wheel but I have some time).
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