[mbchris]

I have a spare set of 19" M2 Competition 788M wheels and are trying to work out if they will fit on a i4 with the 20" wheels. During my investigation, I found the following:

245/40ZR19 98Y
255/40ZR19 100Y
8.5Jx19 ET35
9Jx19 ET42

245/35ZR20 95Y
255/35ZR20 97Y
8.5Jx20 ET35
9Jx20 ET42

- The width of both the 19" and 20" tires are the same.
- The width of the wheels for both are the same.

M2 788M Wheels and Tires
245/35ZR19 93Y
265/35ZR19 98Y
9Jx19 ET29
10Jx19 ET40

Questions:

1. Why the need for the 20" rear arch extension if the width of wheel and tire is the same?
2. If the 20" tire is the same width, it doesn't seem like there will be much more grip. Less ride quality, lower range. Perhaps the compound is stickier.
3. Any thoughts as to the fitment of my M2 wheels? My initial thought was to get the 20" options, then use the 19" from the M2 for longer range if needed.

[Technic]

You are missing the wheel bolt pattern between wheels. The tires and wheels widths are irrelevant at this point.

The M2 wheels are 120x5 pattern, the i4 wheels are 112x5 pattern. The M2 wheels will not fit in the i4.

[mbchris]

Thank you! Bad assumption on my part of the patterns.

Any ideas why the extensions are needed.

[Technic]

Originally Posted by mbchris

Thank you! Bad assumption on my part of the patterns.

Any ideas why the extensions are needed.

The G26 rear fenders are not wide enough for a 10" wide, et39 wheel, it sticks out without the fender flare:

[techwhiz1]

The offset of the first two sets of wheels are the same.

That last set of wheels has a different offset and widths.

That's enough for them not to fit ignoring the bolt pattern and center bore.

[footie]

Originally Posted by mbchris

I have a spare set of 19" M2 Competition 788M wheels and are trying to work out if they will fit on a i4 with the 20" wheels. During my investigation, I found the following:

245/40ZR19 98Y
255/40ZR19 100Y
8.5Jx19 ET35
9Jx19 ET42

245/35ZR20 95Y
255/35ZR20 97Y
8.5Jx20 ET35
9Jx20 ET42

- The width of both the 19" and 20" tires are the same.
- The width of the wheels for both are the same.

M2 788M Wheels and Tires
245/35ZR19 93Y
265/35ZR19 98Y
9Jx19 ET29
10Jx19 ET40

Questions:

1. Why the need for the 20" rear arch extension if the width of wheel and tire is the same?
2. If the 20" tire is the same width, it doesn't seem like there will be much more grip. Less ride quality, lower range. Perhaps the compound is stickier.
3. Any thoughts as to the fitment of my M2 wheels? My initial thought was to get the 20" options, then use the 19" from the M2 for longer range if needed.

Question 1, you are wrong with your width sizes, the rears are actually 285/30x20 and the fronts are 255/35x20 so the rear arch extensions are there for a reason.

[Technic]

Originally Posted by footie

Question 1, you are wrong with your width sizes, the rears are actually 285/30x20 and the fronts are 255/35x20 so the rear arch extensions are there for a reason.

There is a 245/255-20 option for the M50 without fenders flares outside the USA.

[footie]

Originally Posted by Technic

There is a 245/255-20 option for the M50 without fenders flares outside the USA.

Ok didn’t realise that, thanks for clarifying that.

I had just when out and checked for you and on the one I have it’s 255 or front and 285 on rear.

[Technic]

Originally Posted by footie

Ok didn’t realise that, thanks for clarifying that.

I had just when out and checked for you and on the one I have it’s 255 or front and 285 on rear.

The 862 wheels are 245/255-20 in the i4 M50, same wheels optional in the USA M440i GC:

[footie]

Originally Posted by Technic

The 862 wheels are 245/255-20 in the i4 M50, same wheels optional in the USA M440i GC:

I see, totally different wheel to ours in the UK at least, I believe the rim in your image is a BMW individual rim here so not even part of the regular option list.

I haven’t tested it but what the display shows with 100% charge is a range of 248 miles so slightly better than quoted and should improve a little as temperatures increase.

[spamtron]

Originally Posted by footie

I see, totally different wheel to ours in the UK at least, I believe the rim in your image is a BMW individual rim here so not even part of the regular option list.

Would love to know the width and offsets of that optional 20" wheelset you have there on the UK car... would help the rest figure out better wheel options.

[techwhiz1]

Originally Posted by mbchris

3. Any thoughts as to the fitment of my M2 wheels? My initial thought was to get the 20" options, then use the 19" from the M2 for longer range if needed.

Also ignoring what others said.
It is not the 20" wheel that reduces range it's the type of tire.

A super sticky 18" tire of the same width of an all season 20" will have lower range based on rolling resistance. The reason why the wide 20" on the M50 reduces range is because the tires are sticky.

[Space Cadet]

Which then begs the question as to whether you buy the 20” option, bin the OEM tyres and fit what to recover the range? I’m not currently seeing any reason to fit ‘sticky’ tyres for normal road use, and in the UK the poor state of our roads will probably mean changing tyres at an unwanted rate!

[techwhiz1]

Originally Posted by Space Cadet

Which then begs the question as to whether you buy the 20” option, bin the OEM tyres and fit what to recover the range? I’m not currently seeing any reason to fit ‘sticky’ tyres for normal road use, and in the UK the poor state of our roads will probably mean changing tyres at an unwanted rate!

I an to use the OEM gumballs till they wear out.

I checked and Conti makes a DWS-06 Plus is the correct fitment with a load of about 1750lbs rear and 1650lbs front for w combined of close to 7000lbs. So I think they are good enough.
They have a 40-50k mileage rating and I should be able to claw back some range. I run the older tire on my X5 and get really good wear and performance. I also ran the older version on my 335i.

[Technic]

Originally Posted by spamtron

Would love to know the width and offsets of that optional 20" wheelset you have there on the UK car... would help the rest figure out better wheel options.

i4 M50 OEM wheels - 20"

862I
8.5Jx20 ET35 (P/N 36108747310)
9Jx20 ET42 (P/N 36108747311)

868M
8.5Jx20 ET35 (P/N 36115A130F0)
10Jx20 ET39 (P/N 36115A130F3)

[ste0108]

Hi all, on M50 with M tech package is possible to mount a 9.5Jx19 ET42 or ET40 at the rear instead of original wheel 9Jx19 ET42? Is it fully compatible with the suspension and brake disk/caliper? Thanks

[Technic]

Originally Posted by ste0108

Hi all, on M50 with M tech package is possible to mount a 9.5Jx19 ET42 or ET40 at the rear instead of original wheel 9Jx19 ET42? Is it fully compatible with the suspension and brake disk/caliper? Thanks

A 9.5J et42 is 6mm closer to the fender edge than the OEM 9.0J et42.

It will be fine with a 255/40 tire.

[finestbm@gmail.com]

Hi
I have i4 e40
Changed wheels from 19” to 20”
No difference with mileage range
BMW 846M rims with good year tires from G30 2021
Front rims 8×20 et30 Front tires 245/35/20 Rear rims 9x20 et44 Rear tires 275/30/20