[guytanatz]

Since I got my 340i xDrive last September, I have been researching on several upgrades (exhaust, wheels / tires, slight lowering). On the wheel / tire / suspension side of things, which mod creates the clearest upgrade path for the rest? i.e. I would like to keep things as OEM as possible hence I'd like to keep the stock 400m wheels. I'm 100% getting rid of the RFTs (square) and moving to a staggered All-Season. Would this change my suspension options down the road? I have M-Sport package, non-adaptive suspension currently.

[alohasurftoad]

do you currently have the 400m in 18x8 with 225/45/18 square? if so, you will not be able to run the 225/255 staggered setup on the 18x8 +34 square wheels you have now.

if you want the 400m staggered setup as bmw offers it, you will need to obtain 400m rears which are 18x8.5 +47 with 255/40/18.

with the exception of f34, any oem f3x wheel/tire combinaton will not have a problem with contacting any part of the suspension or body if you lower your car.

[guytanatz]

I am 95% sure it's 18x8 front / 18x8.5 rear. (How can I tell for sure?)

[alohasurftoad]

Originally Posted by guytanatz

I am 95% sure it's 18x8 front / 18x8.5 rear. (How can I tell for sure?)

in your initial post you wrote you have runflats square which you are getting rid of. however, if you have 255/40/18 size tires in the rear you have the oem staggered setup.

[guytanatz]

Currently I have 225s square front and back but I thought the wheel width themselves were 8" in the front and 8.5" in the back? Is that possible?

[alohasurftoad]

Originally Posted by guytanatz

Currently I have 225s square front and back but I thought the wheel width themselves were 8" in the front and 8.5" in the back? Is that possible?

it is possible but unlikely. oem mixed performance summer is the staggered setup. if your car came with all season runflats you have 18x8 +34 with 225/45/18 square, which is four fronts all around.

if you could provide pics of the front and back wheel/tires, from a mostly frontal view, i might be able to tell you from the wheel concavity and the stretch on the tire but it would still be difficult from a pic

[guytanatz]

Originally Posted by alohasurftoad

it is possible but unlikely. oem mixed performance summer is the staggered setup. if your car came with all season runflats you have 18x8 +34 with 225/45/18 square, which is four fronts all around.

if you could provide pics of the front and back wheel/tires, from a mostly frontal view, i might be able to tell you from the wheel concavity and the stretch on the tire but it would still be difficult from a pic

Then I can tell you right now it's square, and it's what I really dislike about the stance of the car. I could have sworn that the OEM 400m were 8 / 8.5 but then again I read that on this forum so it's not bible.

edit:
https://f30.bimmerpost.com/forums/sh...d.php?t=592598

"M Sport comes with a choice of two wheels - the 400M 18" split spoke wheels come standard and the 403M 19" bicolor wheel are optional. Both wheels run 225 tires front and 255 tires rear."

[alohasurftoad]

i believe during pre-lci (328/428/335/435) the 400m was available as 18x8 square with all seasons or 18x8, 18x8.5 staggered if you got mixed performance summer. i'm not sure how or what is offered if building nowadays as they keep changing packages and options.

you can run 245/40/18 square if you want more tread. it is the max width on 18x8. here's a member on square 18x8 397's.

http://f30.bimmerpost.com/forums/sho...MMMM+new+tires

[guytanatz]

https://www.carsaddiction.com/en/wheels/bmw/style-400

So it looks like the staggered 400m setup only comes on the GT models. So they make slightly different 400m rims for the rear only between the models?

How can I check on my car? Tires are definitely square, all season RFTs at the moment. This is important because it will determine if I buy new wheels or not. If I can run a staggered setup on these wheels, I'll keep them. If not, I'll get new wheels and tires before the RFTs wear out.

[jh_f30]

I have 397s on my car. Came with the same square setup (225/45R18 on 18x8). The first time I had to replace my rears, I also wanted a staggered setup so I went with 245/40R18s and haven't had any issues so just know they will fit.

However...that tire is 1.2% larger in diameter than stock. I have RWD, but I've read some things about running different sizes on xDrive and the recommended max variance. Might want to look into that first before making any decisions. Like the old adage, measure twice, cut once.

[goj]

I believe that if you have 18s and all season tires from factory then you have the narrow square setup

[guytanatz]

Originally Posted by goj

I believe that if you have 18s and all season tires from factory then you have the narrow square setup

I believe you are correct and I also think it's safer to err on the side of caution.

I went to Mavis to pick a real live person's brain and the tech there wasn't the most helpful, however, he did say that if you change the wheel too much from stock it could throw off sensors in the car that relate to RPM / speedometer readings. How true is this?

When I search on TireRack, can I trust that the staggered wheels I find there will fit my car perfectly? I absolutely do not want a square setup after these RFTs wear out so I have about 5k-10k miles to figure out what I wanna do.

[goj]

Originally Posted by guytanatz

I believe you are correct and I also think it's safer to err on the side of caution.

I went to Mavis to pick a real live person's brain and the tech there wasn't the most helpful, however, he did say that if you change the wheel too much from stock it could throw off sensors in the car that relate to RPM / speedometer readings. How true is this?

When I search on TireRack, can I trust that the staggered wheels I find there will fit my car perfectly? I absolutely do not want a square setup after these RFTs wear out so I have about 5k-10k miles to figure out what I wanna do.

He's right and wrong. Usually it's not the wheel but the tire size.

If you wanted to upsize and stagger you have two choices that I would recommend. Buy some 19inch stock wheels that ppl sell cheap here on forum when they get new wheels.

Or go aftermarket F19x8.5 offset: +35 and R19x9.5 offset: +40-45

On the aftermarket wheels you have 2 options in tire size that will work best. you could go with OEM 19 sizes front 225/40/19 and rear 255/35/19 OR slightly wider 235/40/19 and 265/35/19. Both would keep wheel+tire diameter within 1% of OEM spec and work perfectly for you

[guytanatz]

Originally Posted by goj

He's right and wrong. Usually it's not the wheel but the tire size.

If you wanted to upsize and stagger you have two choices that I would recommend. Buy some 19inch stock wheels that ppl sell cheap here on forum when they get new wheels.

Or go aftermarket F19x8.5 offset: +35 and R19x9.5 offset: +40-45

On the aftermarket wheels you have 2 options in tire size that will work best. you could go with OEM 19 sizes front 225/40/19 and rear 255/35/19 OR slightly wider 235/40/19 and 265/35/19. Both would keep wheel+tire diameter within 1% of OEM spec and work perfectly for you

And this wouldn't rub at all or impact the stock suspension?

Secondarily, would this impact any suspension options later on? It's something I want to consider also.

[goj]

Originally Posted by guytanatz

And this wouldn't rub at all or impact the stock suspension?

Secondarily, would this impact any suspension options later on? It's something I want to consider also.

No, you would be fine with both options with lowering. Both fit with most coilovers but can not guarantee fitting of you will be doing extreme lowering. These tow tires and those wheel setups are frequently run with zero problems on HR sport springs and others and varying coil overs