[BaconDouble]

I have a 2019 340 GT xdrive with the factory optional 19x8" wheels. Tire size is 225/45 R19, it is a square set-up which I was originally partial to, but open to staggered.

I live in an city location with very poor roads and lots of potholes, over 3 years, I have had 2 tire issues. Never bent the wheels, but my run flats saved the day and I was able to limp home.

I'd like to replace the tires to non-run flats and am considering down-sizing to 18" with a little more sidewall for more comfort and pothole protection, however my concern is on the F34, I believe the overall diameter is close to 27" and 19" seems to be the idea visual size, compared to perhaps 18" for the other F30 models. The F34 is just a bigger, longer, car.

I'd also like to get a more performance-oriented ride (this is still my family car but the run flats have aren't very sporty feeling) and also would like to reduce the weight somewhat and go for a wider tire to fill out the wheel well.

Question - what is the consensus on 18" vs 19" for the F34? What is the widest wheel/tire combo I can use in 18" and 19" fitment?

The Apex website states I could run:
18x9” ET30 or ET31 with 245/40-18 tires
18x9.5" ET35 with 255/35-18 tires

or

19x9" ET28 or ET30 with 255/30-19 tires
19x9.5" ET33 or ET35 with 255/30-19 tires
.....however I'm concerned a 30 or 35 series sidewall is shorter than what I have now and would be even worse. Playing around on a tire size calculator it seems these sizes reduce the overall diameter even more. A 255/30R19 tire is only 25" diameter vs my stock 27" diameter. Wouldn't this make a huge gap in the wheel well without lowering?

Also, I'm not sure how much these general sizes apply to the F34 chassis.

Down the road, I'd also like to lower the car slightly (the xdrive plus the F34 chassis I believe is super-high compared to other F30s), and am also looking into the nice mild drop. Any recommendations for lowering springs/shocks or coilovers specifically for the F34?

So in terms or looks, reducing weight/handling, comfort, and tire selection, what would be ideal? I could be talked into a staggered set-up, I do like the looks of a nice wide rear tire.

Sorry for so many questions, it seems F34 specific answers are hard to come by.

[Jvac]

F34 specifics aside, it's still a regular car, f series bmw at that. 18 will definitely ride softer than 19". I'm in the process of downsizing myself, for the same reasons you are. Any other 19" wheel isn't going to make much difference in terms of ride comfort. It's still a very low profile tire. 18" wheels are lighter and the extra inch of rubber is significant. If you're looking to swap wheels the 18" would be the only beneficial option for your scenario. If you look in the owners manual under tire pressure, there's a table that lists all the possible oem wheel options for your car and the corresponding tire pressures. It's helpful in determining what size would fit without any issues so I would start there. Typically a square setup of 245/18 would fit without any issue and offer neutral handling and good grip, but again, see what the owners manual says for the F34 specifically.

[alohasurftoad]

if 18",
18x9 ET30(or31) with 255/45/18 square or
18x9 ET30(or31) front, 18x10.5 ET40 rear with 255/45/18, 285/40/18 staggered

if 19"
19x9 ET30 with 255/40/19 square or
19x9 ET30 front, 19x10.5 ET45 rear with 255/40/19, 285/35/19, staggered

in my search, i couldn't find eibach or dinan springs for your car. imo H&R sport lowers too much for x-drive, proceed at your own risk.

if lowering
KW V1 or Bilstein B14/B16 PSS set to minimum lowering. this is due to aggressive lowering leading to x-drive half shaft failure or unseating.

[oksymoroni]

Originally Posted by alohasurftoad

if 18",
18x9 ET30(or31) with 255/45/18 square or
18x9 ET30(or31) front, 18x10.5 ET40 rear with 255/45/18, 285/40/18 staggered

if 19"
19x9 ET30 with 255/40/19 square or
19x9 ET30 front, 19x10.5 ET45 rear with 255/40/19, 285/35/19, staggered

in my search, i couldn't find eibach or dinan springs for your car. imo H&R sport lowers too much for x-drive, proceed at your own risk.

if lowering
KW V1 or Bilstein B14/B16 PSS set to minimum lowering. this is due to aggressive lowering leading to x-drive half shaft failure or unseating.

I am fairly certain that 255/45/18 will rub in the front. Some people run 255/40/18 and its reportedly a very tight fit. I run 245/40/18 on my Arc8 and I rub at full compression in the front because of my suspension mods.

[BaconDouble]

Originally Posted by oksymoroni

I am fairly certain that 255/45/18 will rub in the front. Some people run 255/40/18 and its reportedly a very tight fit. I run 245/40/18 on my Arc8 and I rub at full compression in the front because of my suspension mods.

This is helpful, I was considering 255 width as well.
Does the F34 use the same front suspension parts as the F30? I think a lot of the rubbing issues might come down to lowering, what suspension type/clearance issues (coil-over vs. OEM style, etc.) and also the wheel offset.

[BaconDouble]

Originally Posted by alohasurftoad

if 18",
18x9 ET30(or31) with 255/45/18 square or
18x9 ET30(or31) front, 18x10.5 ET40 rear with 255/45/18, 285/40/18 staggered

if 19"
19x9 ET30 with 255/40/19 square or
19x9 ET30 front, 19x10.5 ET45 rear with 255/40/19, 285/35/19, staggered

in my search, i couldn't find eibach or dinan springs for your car. imo H&R sport lowers too much for x-drive, proceed at your own risk.

if lowering
KW V1 or Bilstein B14/B16 PSS set to minimum lowering. this is due to aggressive lowering leading to x-drive half shaft failure or unseating.

Thank you- this seems to be a popular option on the F34 threads, what do you think? I'm just looking for a subtle drop, nothing crazy low.

Eibach Prokit springs part # E10-20-031-05-22 and Bilstein B8 Performance Plus Shocks & Struts

[alohasurftoad]

Originally Posted by BaconDouble

Thank you- this seems to be a popular option on the F34 threads, what do you think? I'm just looking for a subtle drop, nothing crazy low.

Eibach Prokit springs part # E10-20-031-05-22 and Bilstein B8 Performance Plus Shocks & Struts

the curb weight of the 340xi Gran Turismo is a little over 4000lbs, which is the highest of the F3/4 series. the extra weight will probably lower it more than an F30,32 or 36 and i'm not sure how or if spring performance is affected. i'd go Koni SA or Sport Yellow for better ride quality over Bilstein B8, however if you prefer Bilstein that's fine.

[johnung]

Originally Posted by BaconDouble

I have a 2019 340 GT xdrive with the factory optional 19x8" wheels. Tire size is 225/45 R19, it is a square set-up which I was originally partial to, but open to staggered.

I live in an city location with very poor roads and lots of potholes, over 3 years, I have had 2 tire issues. Never bent the wheels, but my run flats saved the day and I was able to limp home.

I'd like to replace the tires to non-run flats and am considering down-sizing to 18" with a little more sidewall for more comfort and pothole protection, however my concern is on the F34, I believe the overall diameter is close to 27" and 19" seems to be the idea visual size, compared to perhaps 18" for the other F30 models. The F34 is just a bigger, longer, car.

I'd also like to get a more performance-oriented ride (this is still my family car but the run flats have aren't very sporty feeling) and also would like to reduce the weight somewhat and go for a wider tire to fill out the wheel well.

Question - what is the consensus on 18" vs 19" for the F34? What is the widest wheel/tire combo I can use in 18" and 19" fitment?

The Apex website states I could run:
18x9" ET30 or ET31 with 245/40-18 tires
18x9.5" ET35 with 255/35-18 tires

or

19x9" ET28 or ET30 with 255/30-19 tires
19x9.5" ET33 or ET35 with 255/30-19 tires
.....however I'm concerned a 30 or 35 series sidewall is shorter than what I have now and would be even worse. Playing around on a tire size calculator it seems these sizes reduce the overall diameter even more. A 255/30R19 tire is only 25" diameter vs my stock 27" diameter. Wouldn't this make a huge gap in the wheel well without lowering?

Also, I'm not sure how much these general sizes apply to the F34 chassis.

Down the road, I'd also like to lower the car slightly (the xdrive plus the F34 chassis I believe is super-high compared to other F30s), and am also looking into the nice mild drop. Any recommendations for lowering springs/shocks or coilovers specifically for the F34?

So in terms or looks, reducing weight/handling, comfort, and tire selection, what would be ideal? I could be talked into a staggered set-up, I do like the looks of a nice wide rear tire.

Sorry for so many questions, it seems F34 specific answers are hard to come by.

I see that you live in Philly. I live right over the bridge in NJ and the Philly potholes have taken out my runflat tires too. Based on what you said and my experience, here's maybe a little different perspective.

When I switched from runflats to summer Michelin Pilot Sport 4S and winter Michelin X-Ice tires, there were two big noticeable changes:

1) Ditching the runflats eliminated at least half of the stiff stock ride. Even the nastiest potholes at night on Cottman Avenue were no longer jaw breaking. (Ditching stock dampers for Koni's provided the remainder of my improved ride comfort.)

2) No more tire damage. The non-runflats handled the potholes much smoother.

You don't say what tires you are considering, but if you wish to go with All Seasons, my buddies have had excellent experience with Continental DWS06 PLUS.

My F30 came originally with 18x8 ET34 BMW 400M wheels with 225/45-18 runflats. They had a 26.0" diameter. I upgraded the summer tires to 245/40-18 MPS4S which are 25.7" diameter.

Considering that your stock tires with your 19" wheels are already 27" in diameter, you are already riding on the same actual sidewall height that I am! So I don't believe that you need to spend the money for aftermarket wheels to gain ride comfort and less tire damage.

You can keep your stock wheels and upgrade your tire size to 245/40-19 which is about 26.7" in diameter. It's essentially the same thing that I did on my 18" wheels. 245's have more comfortable ride, better handling on curves and better wide tire look in the rear. (255 tires are too wide for your 8" wheels so that's not an option.)

See attached photo for Eibach springs that would work perfectly with your car. You'll want to install shorter bump stops at the same time (possibly the F80 bump stops) or trim the tops of your stock bump stops with a serrated knife. If you can't find that part# from US retailers, then try Tunershop website to source them from Europe.

Are your shocks standard or Adaptive/EDC? How many miles on your car? No reason to change them if Adaptive, but if they are standard then consider Koni Yellow Sport which are adjustable for comfort.

No reason to consider coilovers since the Eibach drop is probably perfect. But if you get the coilover bug consider KW V2 Street Comfort coilovers.

Hope this helps!

[BaconDouble]

Thanks alohasurftoad, johnung, jvac, and oksymoroni for these replies, so much good information you've shared.

I guess I'll need to reevaluate things as I wish there was a nice wider option available for the F34 platform. I was next to a new X5 M50 and that thing had 22" in the rear, 315 cross section tires. They were so wide

I still think 19" is the way to go for the F34 platform, so perhaps square 255 is the way to go (potential for some rubbing), or, if I want that wider look tire in the rear, will have to live with the downsides of a staggered set-up.

Even the M3/M4 I believe doesn't go much wider than 275 or 285 in the rear, so perhaps I need to just keep that in mind.

[mclovin69x]

Originally Posted by BaconDouble

Thanks alohasurftoad, johnung, jvac, and oksymoroni for these replies, so much good information you've shared.

I guess I'll need to reevaluate things as I wish there was a nice wider option available for the F34 platform. I was next to a new X5 M50 and that thing had 22" in the rear, 315 cross section tires. They were so wide

I still think 19" is the way to go for the F34 platform, so perhaps square 255 is the way to go (potential for some rubbing), or, if I want that wider look tire in the rear, will have to live with the downsides of a staggered set-up.

Even the M3/M4 I believe doesn't go much wider than 275 or 285 in the rear, so perhaps I need to just keep that in mind.

What did you end up going with?

I have an F36 and just ordered the following (but don't know if it's going to fit):
Bayern Antler 18x9.5 ET35
255/40ZR18 Continental ExtremeContact DWS 06 Plus
Bayern Antler 18x9.5 ET45
285/35ZR18 Continental ExtremeContact DWS 06 Plus

alohasurftoad thinks they should clear without rubbing but he's not sure