[MegaMatt3]

Hi all,

I have a '16 M235i, ordered with summer staggered setup. It currently has 225/40 front and 245/35 rear. I'm thinking about going to a square setup so I don't have to keep 2 sets of tires around.

Quick research on TireRack tells me the square setup is all 225/40. What I'd like to do is keep my 2 front wheels, since those are already the right size, and just buy two new ones of the same size. First question: is this a sound plan?

Second question, assuming this is a sound plan. I'm having a hard time finding my OEM part number for my wheels so I can order 2 new ones. Can someone point me to the best place to get this info?

Much appreciated.

[khcoaching]

I went the opposite way....I found 2 OEM rear 8" wheels and ran 245/35/18 square. I had to use 10mm spacers up front, but zero issues other than that with a track alignment.

[MegaMatt3]

Originally Posted by khcoaching

I went the opposite way....I found 2 OEM rear 8" wheels and ran 245/35/18 square. I had to use 10mm spacers up front, but zero issues other than that with a track alignment.

Yeah, so I'm basically interested in switching to whatever the factory setup would have been for all square. I remember having the option for all seasons instead of summer tires, but I can't figure out what the wheel options would have been.

[dradernh]

Originally Posted by MegaMatt3

Yeah, so I'm basically interested in switching to whatever the factory setup would have been for all square. I remember having the option for all seasons instead of summer tires, but I can't figure out what the wheel options would have been.

Just a guess, but I'd expect 18X7½ ET45 wheels with 225/40-18 tires were the base all-square, 130-MPH limit setup sold by BMW in the US.

This is the realoem page for your car, but it's a mess to wade through: https://www.realoem.com/bmw/enUS/par...MW-M235i&mg=36.

[marcthedark]

Why switch the wheels?
You can run 225/40 all around on the 7.5 Front and 8 Back
Or you could run 235/40 all around (technically not recommended on 7.5 but done by many people unless you track)

[MegaMatt3]

Originally Posted by marcthedark

Why switch the wheels?
You can run 225/40 all around on the 7.5 Front and 8 Back
Or you could run 235/40 all around (technically not recommended on 7.5 but done by many people unless you track)

Yeah I don't really want to switch wheels. For cost reasons, I'd like to make use of the 2 front ones I already have and just use that same size (225) on the rear, but I just wasn't sure that was a good strategy. I have little to no experience with this. So you're saying that would work? I just would need to get the model number of my front wheels, and not quite sure how even to get that.

And speaking of having no experience, can you explain what you mean by 7.5 / 8?

[Miata13]

Originally Posted by MegaMatt3

Yeah I don't really want to switch wheels. For cost reasons, I'd like to make use of the 2 front ones I already have and just use that same size (225) on the rear, but I just wasn't sure that was a good strategy. I have little to no experience with this. So you're saying that would work? I just would need to get the model number of my front wheels, and not quite sure how even to get that.

And speaking of having no experience, can you explain what you mean by 7.5 / 8?

I believe he's referring to the respective width of the o.e. wheels of 7.5" front and 8" rear wheels.

I too am interested to learn more about whether it is "feasible" and an acceptable solution to use the different width o.e. wheels fitted with the 225-40-18 wheels AND be able to rotate those wheels front to rear to even out wear. My fronts take a beating on auto-x and track event days due to absence of any available negative camber settings in my 230i xDrive Track Package.

I have researched TireRack Extreme Performance tires and available 225-40-18's all seem to accept wheel widths in this range....has anyone swapped the rear 8" wheels to the front & 7.5" width fronts to the rear with 225-40-18" tires all around? If so, what was your experience? Any issues? Many thanks.

[PiddlyD]

I think part of the problem is here is that those of us who are inexperienced with wheels and tires and more casual auto enthusiasts sometimes confuse the terminology.

I have the factory all-season wheel package all around, with 225/40R18 tires - Pirelli Cinturato P7 all season run-flats.

BMW "my garage" tells me the original factory specs by vin for this car included:

18" Double-spoke wheels, style 436M wit h all-season run-flat tires

And there is a PDF at this link:

https://www.2addicts.com/forums/show....php?t=1132609

That shows that I most likely have code 2TR style 436M (front/rear 18.75 225/40 R18) factory wheels (and I'd need to find a set of factory code 2PG, style 436M rear wheels if I wanted to go 18x8, 245/35 R18 staggered while keeping my factory front wheels.)


The confusion for people like us wo aren't gearheads comes in that the tires are measured in mm (225... 245) and the wheels are measured in inchs (18x7.5 front - 18.8 back).

And that wheels often get called rims - and tires often get called wheels, casually.

I've experienced the back "swaying" in my 16 F23 when merging onto the highway and accelerating hard... it didn't feel like tramlining. I've owned a 97 Mustang GT 4.6 and this feels different - it isn't like the wheels are trying to follow road-ruts - it is like a sway. Even accelerating hard without changing lanes - the back feels like it wants to track in a different direction than the front. I've seen posts of other 235i drivers here describe what sounds like nearly the same experience. I've also heard stories in the past about tuned Bugs, Audi TTs and Porsche Boxsters requiring more rear downforce because of the short wheelbase and aerodynamics tending to make the rear come out at high speeds. The first time I had heard about this was back in the late 80s when I was a teen that owned a tuned Datsun 510 - a friend described tuned Bugs basically having the rear end come all the way around and the whole car spinning circles down the track because they weren't aerodynamically designed to do speeds over 50 MPH. Later when the TT came out, the earliest versions did not have a rear tail, but it was quickly added - and the Porsche Boxster's automatic tail pops out at highway speeds for this reason.

The feeling is also different than the twitchiness of the rear end of an M4 when you stomp on it and it tries to keep all that torque sticking to the ground - different than when you hit a bump or joint expansion in a corner and the back end skips around. The feeling of breaking loose didn't happen at the START of acceleration or during a gear shift with the M235i, but in the middle of it. It also isn't just me - I had my wife test drive it when I bought it and she commented on the same feeling. I don't have it as bad as the other poster - my DSC light isn't coming on just during hard acceleration on the on-ramp, or anywhere else - but the feeling of sway during enthusiastic driving is noticeable.

I figure the first time I take it in for service I'm going to have them look at the rear suspension - and I'll probably take it in for a 4 wheel alignment - but I hate alignment issues - I feel like often alignment is a symptom of something else wrong with the suspension, and just correcting the alignment is an expensive band-aid if you don't fix the problem causing that issue.

And in this case, the advice I've heard makes me wonder if it is just a matter of the tires being square when they should be staggered, and all-season run-flats instead of traditional summer tires.

I'd like a big, open flat surface that I could really open it up on without any walls to put it into if I spun to really get a feel for what is going on.

Anyhow, at the end of this, I realized it kind of was thread hijacking - but I'm in a similar boat to OP with wanting to replace factory wheels - only the reverse - I want to go staggered - and the links I provided may help OP or anyone else reading along who is seeking a similar solution.

[PiddlyD]

And the discussions of the electronic speed limiter being 130 with F2x 235is sold with factory all-season run flats has led me down an expensive rabbit hole where I now think in addition to upgrading the rears to 8.5" 245s, I'm going to need to do an aftermarket tune to remove the limiter.

That seems so stupid to sell a car with a limit based on the wheels it leaves the factory with and make it non-reversible. That means there are two different models of F22/F23 out there as far as top end performance, based solely on the factory tires - and you can't just replace the wheels and rubber and get that limit removed. It seems so arbitrary.

[dradernh]

Originally Posted by PiddlyD

And the discussions of the electronic speed limiter being 130 with F2x 235is sold with factory all-season run flats has led me down an expensive rabbit hole where I now think in addition to upgrading the rears to 8.5" 245s, I'm going to need to do an aftermarket tune to remove the limiter.

That seems so stupid to sell a car with a limit based on the wheels it leaves the factory with and make it non-reversible. That means there are two different models of F22/F23 out there as far as top end performance, based solely on the factory tires - and you can't just replace the wheels and rubber and get that limit removed. It seems so arbitrary.

I'm a long-term track rat, and I'm wondering why a 130-MPH speed limit is an issue for how you're using your car.

I can see it if you're going to be running hard on a track where that limit prevents you from achieving your goals. Otherwise, does it really matter.

Mind you, I've enjoyed a surfeit of triple-digit stops by the speed enforcement brigade, and I tend not to recommend those encounters...to anyone. If only they'd be reasonably polite after pulling me over; however, apparently, that isn't a part of their training.

[Rollo`]

Drader you really seem like someone I would like to share a few beers with.

[freakystyly]

Winter tires typically have a lower speed rating as well.. I'd discourage trying to sustain high speeds on tires that have a low speed rating. Unless of course you like exploding tires at high speeds.

But yeah, it should be a common sense thing. Unfortunately people see fast car and want to go fast regardless if it can handle it.

Whatever speeds you choose drive, try to do it with consideration for other people and also how long it will take to brake afterwards.

[PiddlyD]

Originally Posted by dradernh

I'm a long-term track rat, and I'm wondering why a 130-MPH speed limit is an issue for how you're using your car.

I can see it if you're going to be running hard on a track where that limit prevents you from achieving your goals. Otherwise, does it really matter.

Mind you, I've enjoyed a surfeit of triple-digit stops by the speed enforcement brigade, and I tend not to recommend those encounters...to anyone. If only they'd be reasonably polite after pulling me over; however, apparently, that isn't a part of their training.

So, I'm aware of speed ratings (and the Pirelli run flats are actually speed rated above the factory 130 limit, but regardless...)

I think I said I plan on replacing the tires with speed rated summer tires. I don't remember - but I do plan on finding a pair of 8.5" rears and putting 225 front and 245 rear rubber on them.

I've also experienced triple-digit stops by highway patrols. I did get let off with just a warning by a very friendly guy who noted when I was maneuvering through traffic at around 85mph, I did signal every lane change. My recommendation, handle any high speed stop like a felony stop. Throw your keys out the window and keep your hands out the window until the cop tells you to put them on the steering wheel.

It *does* matter to me that I should be able to decide the prudent top speed for my abilities, vehicle, and equipment - not engineers in Germany who made the arbitrary decision that the factory tire option should forever limit the car to a top speed they feel is suitable for those tires. I doubt I'll ever hit that limit - but if I decide I want to, I think I should be the one making that decision, not my ECU.

Fair enough?

I live in the west, and I do a lot of driving along desolate, empty stretches of long highway - although most of my high speed stops have been on Highway 50 in Sacramento between Folsom and Downtown Sacramento.

I mean, if you were buying a 235i, and there were two that were identical - but one had been purchased with all-seasons and had a 130 top end limiter, and the other had been bought with staggered summer tires with a 160 top end limiter...

Which would you buy?

Rhetorical question.

[Vroomtuber]

I went with a square setup & aftermarket wheels - 18 x 8.5 ET 35 with PS4 245/35. You will need -1.5 of camber up front (I set with he SPL Arms) and -1.8 camber in the rear, which can be adjusted with the OEM arms.

Anything more would require spacers.