[Replicant]

Does anyone know if a squared tire setup on staggered wheels is acceptable for xdrive? So for instance if you have 8.5 width on the front and 9.5 width on the back, but put the same exact tire on both ends, would you be running foul of xdrive specs ? Would the fact that the tire is stretched a bit on the rear rim cause a difference in rolling diameter? My understanding is that with steel belted radials the circumference does not change, at least in any meaningful way, but I am wondering if others have done this, and if you have encountered any issues.

[Bilbofraggins]

We had an F25 with a stock square set up... now my sons vehicle.

I put a square winter set up on our new G01... and have used a square winter setup on my X6M for the last 6 years without issue...

[Rbrown]

I have staggered summers and square for F25 and G01.

All BMW approved.

[Replicant]

Originally Posted by Bilbofraggins

We had an F25 with a stock square set up... now my sons vehicle.

I put a square winter set up on our new G01... and have used a square winter setup on my X6M for the last 6 years without issue...

Just to clarify, you are running that square tire setup on factory staggered size wheels?

[Replicant]

Originally Posted by Rbrown

I have staggered summers and square for F25 and G01.

All BMW approved.

Right, but is that square setup on staggered wheel rim sizes?

[HighlandPete]

Originally Posted by Replicant

Right, but is that square setup on staggered wheel rim sizes?

They won't be, if "BMW approved".

BTW, why would you want the same size tires on rims with a 1" difference in width? What driving characteristics are you trying to achieve?

[Replicant]

Originally Posted by HighlandPete

They won't be, if "BMW approved".

BTW, why would you want the same size tires on rims with a 1" difference in width? What driving characteristics are you trying to achieve?

I’m not trying to achieve a driving characteristic. I’m just wondering if anyone has squared up tires on staggered wheels for simplicity sake.

[Climb Mode]

Originally Posted by Replicant

I’m not trying to achieve a driving characteristic. I’m just wondering if anyone has squared up tires on staggered wheels for simplicity sake.

I did on my F30 xDrive. Staggered wheels, used square 245's all around for winter set up.

It's all about tire compliance with the different wheel widths. Wheels widths have nothing to do with xDrive. The car doesn't know what width wheels it's driving on, it's all about the tire that is making contact with the pavement

[HighlandPete]

Originally Posted by Replicant

I’m not trying to achieve a driving characteristic. I’m just wondering if anyone has squared up tires on staggered wheels for simplicity sake.

I'm aware of users fitting the same size tires on staggered rims where the difference is 0.5". For example, 225 section on 8/8.5" rims. Both fall within the standards.

When the rims are 0.5" (let alone 1.0") different, you would normally change the tire section/width by 5mm. Will depend where the tire sits regarding the measuring rim and what the relevant tire standard is. (UK, we work with ETRTO & DIN standard).

From the Continental Technical Databook.

In the event of a change in the rim width by + ½ inch, the tyre width changes by approx. + 5 mm.

BTW, what tire size are you considering? One that fits between the two sizes used for a staggered set?

[Replicant]

Originally Posted by Climb Mode

I did on my F30 xDrive. Staggered wheels, used square 245's all around for winter set up.

It's all about tire compliance with the different wheel widths. Wheels widths have nothing to do with xDrive. The car doesn't know what width wheels it's driving on, it's all about the tire that is making contact with the pavement

I am with you on this. The tire size I am talking about is within the acceptable range for both rim sizes, and is also a BMW approved tire for this vehicle. Where the question comes in, is the fact that the tire is "stretched" a bit on the rear wheel (still within acceptable range) vs the tire in the front being on a narrower rim, going to cause an issue with the xdrive due to a (technically) different in tire diameter. Does the rolling diameter of the rear tire vs the front change at all due to them being on different size wheels? (because the section width changes)?

This article seems to indicate that while technically it would change since the section width changes and is part of the calculation of wheel diameter, with regard to a steel belted radial, there is really no change.

https://www.tirerack.com/tires/tiret...jsp?techid=194

A tire's section width (also called 'cross section width') is the measurement of the tire's width from its inner sidewall to its outer sidewall (excluding any protective ribs, decorations or raised letters) at the widest point. This measurement is made without any load placed upon the tire and after the tire has been properly mounted on its industry assigned measuring rim and has been inflated and reset to its test pressure after 24 hours.

Because a tire's section width is influenced by the width of the rim upon which the tire is mounted, the correct industry assigned measuring rim width for the tire size being measured must be used.

The width of a tire mounted on a narrow rim would be 'narrower' than if the same tire was mounted on a wide rim.

Note: Because the overall diameter of a steel belted radial is determined by the steel belts, there is little, if any, change to the overall diameter of the tire due to differences in rim width.

The industry rule of thumb is that for every 1/2" change in rim width, the tire's section width will correspondingly change by approximately 2/10".

[HighlandPete]

Originally Posted by Climb Mode

I did on my F30 xDrive. Staggered wheels, used square 245's all around for winter set up.

It's all about tire compliance with the different wheel widths. Wheels widths have nothing to do with xDrive. The car doesn't know what width wheels it's driving on, it's all about the tire that is making contact with the pavement

RC is calculated using the measuring rim size for any particular tire. Rim width could slightly change the RC, depending on where the tire sits, in relationship to the measuring rim size for the tire used.

If it is different, then xDrive has to rely on tire tolerance logic to accommodate the rotational speeds. Not so critical on a same size tire, front and rear, as some staggered combinations. Tire pressure variations, front to rear, likely has more influence on RC, than the 0.5" difference in rim width.

[Replicant]

Originally Posted by HighlandPete

I'm aware of users fitting the same size tires on staggered rims where the difference is 0.5". For example, 225 section on 8/8.5" rims. Both fall within the standards.

When the rims are 0.5" (let alone 1.0") different, you would normally change the tire section/width by 5mm. Will depend where the tire sits regarding the measuring rim and what the relevant tire standard is. (UK, we work with ETRTO & DIN standard).

From the Continental Technical Databook.



BTW, what tire size are you considering? One that fits between the two sizes used for a staggered set?

245

245 fits in the ideal range for 8.5 and the minimum size for 9.5.

[Bilbofraggins]

Same size rims...my bad..should have clarified

[edw0000000]

Something i found on YouTube

[F30.N54.lol]

My winter tires are "square" on a staggered rim setup .....NO ISSUES ON MY X40M. I do this only for Winter to get equal contact patch for inclement winter weather.

I would highly recommend you get staggered sizes if they are your only tires (all season) / summer tires so you can get that amazing handling feel.

[coolguywalt]

Originally Posted by F30.N54.lol

My winter tires are "square" on a staggered rim setup .....NO ISSUES ON MY X40M.

What size tire combo are you using? Found a good deal on some slightly used 245/45/R19 Pirelli Sottozero 3 runflats I was interested in picking up.