[PLF69]

Originally Posted by G80M4

car came with 225 front 255 rear staggered p zero run flats

what difference will it make the car's handling if i went 255 all around?

Car will be much less understeer prone, more neutral maybe even a lot easier to oversteer.

These are my observations running square 245, this season I will be running 255 square.

[mass340]

Is anyone running the 245 squared set up with spacers and lowered? If so any rubbing problems?

[kohlzor]

Originally Posted by BarryB

245/40
265/35
Nope or at least per the dealer and from what I can tell so far. They feel great. 265/40 on the other hand DID NOT work.......

I ended up ordering 2 8.5" as well to copy your setup. Do I need to be cautious of what tires to get or any should work as I don't think rubbing is going to be an issue with this setup.

[BarryB]

Originally Posted by kohlzor

I ended up ordering 2 8.5" as well to copy your setup. Do I need to be cautious of what tires to get or any should work as I don't think rubbing is going to be an issue with this setup.

If you have xdrive you need to follow my sizes ( brand less issue) to maintain the correct rolling circumference. If not xdrive you have many more options.

[kohlzor]

Originally Posted by BarryB

If you have xdrive you need to follow my sizes ( brand less issue) to maintain the correct rolling circumference. If not xdrive you have many more options.

Originally Posted by BarryB

If you have xdrive you need to follow my sizes ( brand less issue) to maintain the correct rolling circumference. If not xdrive you have many more options.

Yup it's xDrive and gonna use the same size as yours

[mass340]

Originally Posted by BarryB

If you have xdrive you need to follow my sizes ( brand less issue) to maintain the correct rolling circumference. If not xdrive you have many more options.

Are you lowered?

[BarryB]

Originally Posted by mass340

Are you lowered?

No but i had spacers. The larger tires gave the look of lowered by decreasing the wheel well gap. and fyi I sold her

[kohlzor]

Originally Posted by BarryB

No one talks (or maybe knows) about slip angle and why I didn't add spacers... the effect is certainly not noticeable on any type of street driving with my "over tire" compared to stock. I'd even go as far to say it (handling) is much better than with the run flats......
Adding spacers improves the looks but "could" slightly effect the handling by changing the slip angle so have held off (for now).
PS an 8" rim is ok for a 245 P4s per Michelin's website.....

Ah would the dw06 fit the 8" didn't realize it could vary that much per manufacturer.

[kohlzor]

Originally Posted by BarryB

No but i had spacers. The larger tires gave the look of lowered by decreasing the wheel well gap. and fyi I sold her

What tire pressure did you end up running with the new setup?

[BarryB]

Sorry I don't recall anything different from stock pressures

[kohlzor]

Originally Posted by BarryB

Sorry I don't recall anything different from stock pressures

No worries! I got the exact same sizes installed today and they look great and no rubbing. Thanks for the suggestion.

[BarryB]

Originally Posted by kohlzor

No worries! I got the exact same sizes installed today and they look great and no rubbing. Thanks for the suggestion.

Awesome, congrats.

[Assassin]

Its the rolling circumference of the tyres across each axle and front to rear that must be kept as close as possible on an X-Drive. The reason is that the transfer box which distributes the drive to the front and rear wheels contains clutches. When you turn a corner all the wheels are turning at different speeds and these clutches have to slip a little to avoid drivetrain windup. [Windup can cause steering, juddering and wheel skipping issues and was evident in much older, direct four wheel drive set ups.]

This clutch slippage obviously causes wear over time. When travelling in a straight line all the wheels are turning at the same speed so no slippage. If your tyres / wheels are 'mismatched' i.e. not the same rolling circumference then these clutches have to compensate by slipping slightly all the time causing excessive wear over time and potentially causing transfer box issues / failures.

Differences in tyre rolling circumference can be caused by mismatched wheel /tyre sizes, different tyre brands [or even models within brand] and pressure. Its why 'BMW approved' tyres are recommended as they are made to tighter tolerances.

Some people have no issues regardless of tyres fitted. Others have had lots of transfer box issues and some have had warranty work on the transfer box declined because of non-approved wheel / tyre fittments.

There are several tyre diameter comparison sites to try before you buy such as:
https://tiresize.com/tyre-size-calculator/

I became aware of this issue having just bought my previous F31 335d M Sport Touring and badgered the dealership "BMW Expert" until he got me the official BMW position on this as there were so many opinions on-line. See my post #37 here for the official BMW reply:

https://f30.bimmerpost.com/forums/sh...1142647&page=2

[omair335]

275/35 r19 Federal RS- Pros on my RWD M340i. Lots of room on suspension side to spare. Probably could fit a 295 with some rolling.

[Wet Fish]

I'm really sorry, but I've read through a bunch of posts and not sure if this setup will work on my M340i XDrive for a Square setup:

19x8.5
235/40/19 with 25mm offset (would it be best to have the same on both axles?)

I'm basically looking for the most balanced setup whilst getting the wheels flush. Someone please help a novice out. Would that be okay or should I try and find wheels with a smaller offset, maybe 20mm?

[Ravenseal]

This thread seems a little bit more alive than the fitment thread on the G42 forums. Here is my 245/40/19 fitment up front on stock 791M 8" wheels - replacing OEM 225^2. Any thoughts on these gaps? Slightly worried about the gap between the top of the tire and the sprint perch. No rubbing yet…

[PLF69]

Ravenseal

I think it will be fine but why not run 245/35-19 when the rear is 255/35-19 ? Much closer to the same rolling diameter...

[Insane435]

So, have we answered the question on what the max square setup is? There is another thread where Apex wheels posted their offerings. If you take the specs and put it into the comparison calc, I believe you can run 265/35/19 x 9" squared. You will need to play with the offsets front/back and maybe use a spacer. To me, it seems like the 265s are possible.

There is even a member who is running 265s.

[FellowM3]

Still confused about the definitive staggered approved sizes for xdrive

Also, if my car came squared, switching to staggered with a ~1% rolling circ difference shouldn’t matter right ?

[PLF69]

Originally Posted by FellowM3

Still confused about the definitive staggered approved sizes for xdrive

Also, if my car came squared, switching to staggered with a ~1% rolling circ difference shouldn’t matter right ?

Yep, if your Xdrive just keep the difference in rolling diameter between front and rear below 1%

Above that your exposing yourself to transfer case issues.

[FellowM3]

Originally Posted by Insane435

So, have we answered the question on what the max square setup is? There is another thread where Apex wheels posted their offerings. If you take the specs and put it into the comparison calc, I believe you can run 265/35/19 x 9" squared. You will need to play with the offsets front/back and maybe use a spacer. To me, it seems like the 265s are possible.

There is even a member who is running 265s.

Did you ever e d up installing 265s squared. Would love to see this and being squared will prolong tire life longer as I can swap rear and fronts

[Ravenseal]

Originally Posted by PLF69

Ravenseal

I think it will be fine but why not run 245/35-19 when the rear is 255/35-19 ? Much closer to the same rolling diameter...

I'm on xDrive, so it's 245/40 squared. I tried to order 245/35 but Pilot AS4 in that size were backordered at Discount Tire.