[FastMFurious]

Hey guys, I'm new to the forum and a first time BMW owner! I just bought a 2023 M550i with xDrive. I am wanting to get a new set of wheels and tires because the run flats I have kind of suck. I have also read how some people on here can easily get flats after hitting potholes with run flats tires. My stock tires are 245/35/20 & 275/30/20. I am considering running 255/40/19 & 285/35/19 (non-run flat). I just don't know how wide of a wheel I can safely fit under the fenders. I don't plan on lowering the car. The fitment calculators people have been posting on here have helped me choose a good tire size, but I am having difficulty with figuring out how wide of a wheel will fit. I would like to have 9.5" in the front and 10.5" in the back. Has anyone run wheels this wide on their 5 series?
The wheels I am looking at are the VORSTEINER V-FF 107 in Carbon Graphite. I believe they have a +30 offset.
Any help would be appreciated.

Thanks!

[pperc]

I’ve seen most run 9 and 10.5 with those tires comfortably

[FastMFurious]

Originally Posted by pperc

I’ve seen most run 9 and 10.5 with those tires comfortably

I think you might be right.

I could not find the stock wheel specs for my wheels so I went outside and measured. It looks like my front wheels are 9" wide and my rear wheels are 10" wide. If my super high tech measuring tools (weighted string and tape measure) are accurate, my front offset is 38mm and my rear offset is 50.8mm. With the help of https://www.willtheyfit.com/ I should be able to figure out how wide I can go. I will probably end up just getting 19x9 and 19x10.5 like you said.

[tjbuggy2b]

I have a 540ix, which is the same as your 550i, regarding tire/wheel fitment.

After a lot of research on trying to max out the concavity of the wheels I wanted, I just ordered a set of 20x9 et30 and 20x10.5 et 40. This is not an extreme fit, in terms of poke but I don't like poke. I like just shy of flush, that "OEM+" look that people are calling things now. I'll be running 255/35r20 and either 285/30r20 or 295/30r20. If I feel I can get a tad more aggressive, I'll then add small spacers.

9.5 "can" fit on the front but you have to run a pretty aggressive offset, or a spacer with a less aggressive offset. From what I've seen, et25 is about least aggressive offset you can run on that size, due to suspension interference, and it may still require a spacer. Either way, you'll probably have a bit of poke, which may force you to run a stretched tire (like a 255, which is pretty stretchy on a 9.5" wheel, imo) in order to clear the fenders, if you lower it. I hate stretched tires. So, opted against it.

10.5" rear is totally fine. 11" is probably the same at the 9.5" front. All depends on offset.

One thing to caution, which is why I haven't decided quite yet on tire size is that, for AWD cars, it's recommended to keep the overall diameter difference between front and rear less than 1%. Running the 285/30r20 rear sits at 1.1% or 1.2%. Some people say they have had no issues running that size but I've seen a person or two complain about drivetrain noises and possible stability control glitches.

295/30r20 is definitely the safer route, with the 255/35r20 front.

Anyway, very few people run a 9.5" front, and even less run an 11" rear. I've found maybe 2 or 3 pics of either of those on the interwebz, and none of the commentary surrounding them were what I'd consider definitive.

One last thing to consider is that different tire brand can vary slightly in diameter, width, and profile, regardless of what the stated actual dimensions are. I've been told by Fitment Industries that Continental and Michelin tend to run a little bigger than others, though they didn't say by how much. So, that's kind of an unknown.

YMMV

For what it's worth, I plan on taking a bunch measurements after they're installed to try to put a finer definition on what should fit. However, it'll be a couple months before my wheels get here. So, I may not have them mounted until spring, which isn't a lot of help for you.

[pperc]

Originally Posted by tjbuggy2b

I have a 540ix, which is the same as your 550i, regarding tire/wheel fitment.

After a lot of research on trying to max out the concavity of the wheels I wanted, I just ordered a set of 20x9 et30 and 20x10.5 et 40. This is not an extreme fit, in terms of poke but I don't like poke. I like just shy of flush, that "OEM+" look that people are calling things now. I'll be running 255/35r20 and either 285/30r20 or 295/30r20. If I feel I can get a tad more aggressive, I'll then add small spacers.

9.5 "can" fit on the front but you have to run a pretty aggressive offset, or a spacer with a less aggressive offset. From what I've seen, et25 is about least aggressive offset you can run on that size, due to suspension interference, and it may still require a spacer. Either way, you'll probably have a bit of poke, which may force you to run a stretched tire (like a 255, which is pretty stretchy on a 9.5" wheel, imo) in order to clear the fenders, if you lower it. I hate stretched tires. So, opted against it.

10.5" rear is totally fine. 11" is probably the same at the 9.5" front. All depends on offset.

One thing to caution, which is why I haven't decided quite yet on tire size is that, for AWD cars, it's recommended to keep the overall diameter difference between front and rear less than 1%. Running the 285/30r20 rear sits at 1.1% or 1.2%. Some people say they have had no issues running that size but I've seen a person or two complain about drivetrain noises and possible stability control glitches.

295/30r20 is definitely the safer route, with the 255/35r20 front.

Anyway, [...]

Couple of things:
Lower the offset number, the more aggressive it is.
OEM staggered 20s are -1.1% so I wouldn’t worry too much about that difference.

[tjbuggy2b]

Originally Posted by pperc

Couple of things:
Lower the offset number, the more aggressive it is.
OEM staggered 20s are -1.1% so I wouldn’t worry too much about that difference.

Yes, I don't think I said the contrary, regarding offset. If I implied it, maybe just poor phrasing. ...or you're bad at reading. (Jokes, people. Just jokes.)

Regarding %diff, yeah, that's true. I just wonder why some people have reported issues with it.

[tjbuggy2b]

Here is a tire size chart I made to help in my decision making process. It's less to do with wheel size but may still help. Hope it makes sense. It was just thrown together for my own use.

As you may see, my preferences didn't necessarily align across all of the metrics. So, I compromised my desired sidewall to achieve my desired wheel to tire width difference to avoid too much stretch.

Blue cells are sizes I've run before and liked, though on a different car. Mainly just there for sidewall and wheel/tire width difference comparison.
Bold are stock sizes for the G30.
Green cells were size within my personal spec preferences.
Orange cells were pushing the limit of what I wanted.

[FastMFurious]

Originally Posted by tjbuggy2b

After a lot of research on trying to max out the concavity of the wheels I wanted, I just ordered a set of 20x9 et30 and 20x10.5 et 40. This is not an extreme fit, in terms of poke but I don't like poke. I like just shy of flush, that "OEM+" look that people are calling things now. I'll be running 255/35r20 and either 285/30r20 or 295/30r20. If I feel I can get a tad more aggressive, I'll then add small spacers.
9.5 "can" fit on the front but you have to run a pretty aggressive offset, or a spacer with a less aggressive offset. From what I've seen, et25 is about least aggressive offset you can run on that size, due to suspension interference, and it may still require a spacer. Either way, you'll probably have a bit of poke, which may force you to run a stretched tire (like a 255, which is pretty stretchy on a 9.5" wheel, imo) in order to clear the fenders, if you lower it. I hate stretched tires. So, opted against it.
10.5" rear is totally fine. 11" is probably the same at the 9.5" front. All depends on offset.

Thanks for the reply tjbuggy2b! This was really helpful and confirms what I wasn’t sure about. I basically have the same taste in how a wheel setup should look. I want it to be just inside the wheel well and I hate the look of stretched tires. I would like the sidewall to be square with the wheel. Maybe have a tiny bit of tire hang over the wheel to help protect against slight curb rubbing.

Originally Posted by tjbuggy2b

One thing to caution, which is why I haven't decided quite yet on tire size is that, for AWD cars, it's recommended to keep the overall diameter difference between front and rear less than 1%. Running the 285/30r20 rear sits at 1.1% or 1.2%. Some people say they have had no issues running that size but I've seen a person or two complain about drivetrain noises and possible stability control glitches.
295/30r20 is definitely the safer route, with the 255/35r20 front.
Anyway, very few people run a 9.5" front, and even less run an 11" rear. I've found maybe 2 or 3 pics of either of those on the interwebz, and none of the commentary surrounding them were what I'd consider definitive.
One last thing to consider is that different tire brand can vary slightly in diameter, width, and profile, regardless of what the stated actual dimensions are. I've been told by Fitment Industries that Continental and Michelin tend to run a little bigger than others, though they didn't say by how much. So, that's kind of an unknown.
YMMV

One thing I found with https://tiresize.com/calculator/ is that when I compared a 255/40/19 with a 285/35/19 is that there is only a -0.4% difference in circumference. The front has 746 Revs per mile while the back has 751 revs per mile. Stock was like +1.1% or something. I also found out that this setup has the least effect on the speedo that I could come up with. I will only be off by 1 mile per hour VS stock.
The 2 brands I am considering are the Michelin and Continental so I will keep that in mind about them running bigger.
After reading these posts I think I will go with a 19x9 and 19x10.5 and make up any slack with spacers if I need them. Whatever I end up going with, I will post pics on here. Thanks again guys!

[tjbuggy2b]

Just so you know, the 255/35r20 and 295/30r20 is .2% difference, in case you'd prefer 20" wheels.

[pperc]

Originally Posted by tjbuggy2b

Just so you know, the 255/35r20 and 295/30r20 is .2% difference, in case you'd prefer 20" wheels.

Would these in Michelin 4S fit on a 9 and 10.5? What offsets to get flush? 25 and maybe 42?

[tjbuggy2b]

Sure. When I spoke of size fluctuations, it's not enough to prevent fitment. More just about one might fit a little more to ones liking, than the other.

Those offsets should work but might be close to the fender on the front.

[FastMFurious]

Originally Posted by tjbuggy2b

Just so you know, the 255/35r20 and 295/30r20 is .2% difference, in case you'd prefer 20" wheels.

Yeah, I would like to keep 20s. The main reason why I'm getting new tires is to have a softer ride. I thought with 19s I could have a taller sidewall which would give me more cushion for the bumpy roads in my area.
After thinking about it, I'm just going to get 20" non run flat tires for the wheels I have now and see if they are soft enough for these bumpy roads. I'll get wheels later if I really need 19s or get 20s in a cooler style.

[tjbuggy2b]

When I went from RFT to NRFT on both a Mini Countryman and a 335i, I felt the ride was noticeably less harsh, even though I went to KW coil overs (lowered ~1.5") on both cars.

Obviously, the lower the profile, the harsher things will get. But on these two cars, the difference wasn't too much. Pics below for reference about sidewall esthetics.

Mini Countryman: 225/50r17 ---> 235/40R18 (16% lower profile)
BMW 335i: 225/45r17 ---> 235/40r18 + 265/35r18 (7-8% lower profile)

245/40r19 ---> 255/35r20 + 285/30r20 would be 9% and 13% lower profile.
245/40r19 ---> 255/35r20 + 295/30r20 would be 9% and 10% lower profile.

Actually, as I'm typing this, I think I've made up my mind on tire size to go with the 295/30r20 on the rear for a little more peace of mind for pot holes and a little extra compliance. Pot holes aren't super bad where I live but do exist. Since I ordered forged wheels, I'd like to preserve them as long as possible. Also, I'm sure the 540i is a much heavier car than what my Countryman was. So, I suspect there won't be as much forgiveness (comfort-wise) for lower profile tires.

Something to think about: I did the whee/tire swap at the same time I did the coilovers. So, it's not impossible that some of this better ride feel was due to how good KW CO's are. I'm likely going with MSS springs, this time around because KW only offers the V3 for this car. $3500 is a bit steep for just wanted a lowered car without sacrificing ride quality. MSS is getting rave review on ride quality. ...but I'm getting off topic.