[On3Bad40]

IS THIS TIRE FITMENT SAFE TO RUN ON M340 Xdrive Sitting on Supra wheels ?

[NLJ]

Seems risky on XDrive.
You want to keep diameter under 1%.

[On3Bad40]

Is it 1% or 3% ? I been hearing that it’s 3 . Correct me if I’ve been misinformed

[tturedraider]

Pretty positive it’s not just 1%. I just checked with Tire Rack about going from 225/45 18 to 235/45 18 on a set of winter tires. They said that 235/45 was an approved size for xDrive. The differences in diameter and circumference are identical to those of the tire sizes you posted.

edit: yeah, I was thinking of a square setup, just thinking about the slightly taller sidewall on all four tires. Wasn’t thinking about the percentage difference between front and back on a staggered setup.

[upstate650]

Originally Posted by tturedraider

Pretty positive it’s not just 1%. I just checked with Tire Rack about going from 225/45 18 to 235/45 18 on a set of winter tires. They said that 235/45 was an approved size for xDrive. The differences in diameter and circumference are identical to those of the tire sizes you posted.

The problem for OP is the difference in circumference between front and rear wheel on an x drive. A minor change in tire size isnt an issue, so long as the diameter of front and rear stays almost the same, otherwise he will have problems with the differential. The OP needs to go with a 285/30 or 295/30 if he is going to run 255/35 on the front.

You can certainly run 235/40in a square set up without an issue, which is what I presume you are doing.

The OP says he has Supra wheels, which are either 10” or 10.5” wheels on the rear. Either way, a 265 tire is going to look stupid stretched on those wheels, so simply from an aesthetics standpoint, he will want a 285 or 295 tire.

[NLJ]

Originally Posted by tturedraider

Pretty positive it’s not just 1%. I just checked with Tire Rack about going from 225/45 18 to 235/45 18 on a set of winter tires. They said that 235/45 was an approved size for xDrive. The differences in diameter and circumference are identical to those of the tire sizes you posted.

It’s the difference between front and rear. Upsizing all 4 as a square setup is fine. 235 is also recommended here at some tire shops. But it kinda increases the height of the car as well!

[mondayze]

Diameter is the only thing that matters and I would keep it under 1% to be safe. BMW factory tires are -.4% different in diameter. I run 285/35/19 and 255/40/19 which is the same -.4% diameter difference.

[mondayze]

The 265 tire on a rim wider than 9.5" will not cover the lips.

[upstate650]

Originally Posted by mondayze

Diameter is the only thing that matters and I would keep it under 1% to be safe. BMW factory tires are -.4% different in diameter. I run 285/35/19 and 255/40/19 which is the same -.4% diameter difference.

295/40 will result in the same .4% difference, just slightly bigger than front instead of slightly smaller. Have you tried to run the 295? Would love to on my summer set, but worried about rubbing.

[mondayze]

Originally Posted by upstate650

295/40 will result in the same .4% difference, just slightly bigger than front instead of slightly smaller. Have you tried to run the 295? Would love to on my summer set, but worried about rubbing.

dont need that much tire

[On3Bad40]

How about 275/35/19 and 245/40/19 ? Would the 275 still be stretched ? The 265s would of been r888 . The 275s would be pilot super sports

[jiimmmayyy]

I’ve been on this topic with myself having a set of Supra wheels. I’m xDrive as well and I ran the stock Supra tires and experienced a lot of jerkiness on acceleration. The diameter difference on the stock Supra wheels is about 2%. With like a days worth of AWD research, 1% diameter difference or something close should be okay. I’m planning to run either 235/35 265/30 or 245/35 275/30. Others have ran this on their xDrive staggered 9 wide fronts and 10 wide rears. Sure looks good with spacers on the front though

[Assassin]

See below:

Originally Posted by Assassin

The "1% Myth" question is often asked.............

I posted the information below on another thread in Dec 2018. It was obtained direct from BMW.

--------------------------------------------------------------------------------------------------

The explicit position from BMW is given here:

Extracts from an email chain between myself and the BMW Genius at the dealership I bought my car from when I asked for precise information on this subject amongst others....

The question I asked:....................

"Hi xxxxx, thanks for your help in this matter, but I'm afraid it doesn't really answer my question.

As I mentioned the BMW forums are alive with transfer box issues and queries relating to tyre fitment. Having just spent over £40k on a new Xdrive I would like the official BMW UK guidance on the key factors to be considered when monitoring tyre wear / fitting new tyres to a model with Xdrive so that I can avoid any premature wear / failure of the component.

The UK owners manual gives no meaningful guidance or dos/ don'ts other that use star rated tyres. For my specific model [2018 F31 335d Xdrive Shadow Edition - staggered 19" 704M wheels] I would like to know if:

1) the make / tread depths on tyres across the same axle must be the same or within a specified tolerance. If so, what is that tolerance?

2) is there [as seems to be case in the US i.e. ~1% ] a specific ratio between the rolling circumference of front / rear tyres that must be maintained to minimise stress on the transfer box? If so, what is that tolerance?

These factors are deemed to be critical by all the guys in the UK/US who have had transfer box problems / failures / replacements. At least BMW USA seem to expressed a view on the acceptable ration between the rolling circumference of front v rear tyres on the xdrives to avoid transfer box problems.

Can you please forward my query to the relevant BMW technical department specialists and get them to provide the relevant information. I am happy to be contacted direct should they prefer that approach to ensure clarity.

Please see the links below which are a small example of the issues posted. There are many more:

Tolerance discussion ~1%

https://f30.bimmerpost.com/forums/se...58921360&pp=30

https://www.bimmerforums.co.uk/forum...rchid=31358615

Regards "
---------------------------------------------------------------------------------

The reply I got back eventually........

"I have had another reply from BMW. This should provide an appropriate answer hopefully.

Regards,

The following information taken direct from AIR states a maximum 2mm between all tyres on an X Drive vehicle.
Its in black and white direct from BMW. Problem solved .
Repair instruction
Notes and specifications for tyre / wheel exchange
3612... | REP-ALG-RAGRP36-3600_REIFENTAUSCH - V.6
ui-button
General:
•The tyre size, manufacturer and tyre tread must be the same on one axle
•To meet the BMW standards, the vehicle should be equipped with tyres from the same manufacturer and with the same tyre tread (tyres approved by BMW) on all 4 wheels
•The difference in tyre tread depth on one axle must not exceed 2 mm (control quality of suspension control systems and wheel alignment requirement)
•The tyres with the higher tread depths must be mounted on the rear axle
•The DOT age difference must not exceed 4 years
•The tyre pressure must be adjusted when the tyres are exchanged
•Wheel exchange between the axles
The wheels may be exchanged between axles to achieve even abrasion. However, BMW does not recommend switching the front wheels to the rear or vice-versa.
The wheel exchange may lead to the following customer complaints:

complaints regarding acoustics

Risk of increased lane groove sensitivity
Compliance with the following requirements is required when exchanging wheels between the axles:

Assess the wear pattern

The tread difference between the front and rear wheels must not exceed a maximum of 2-3 mm

Exchange the wheels between the axles every 5000 Km
**Additionally for all-wheel drive vehicles: **
•The tyre size, manufacturer and tyre tread must be identical on all wheels; different tyre sizes between front and rear axles are only permissible if mixed tyres are fitted.
•The tyre tread difference between tyres in all wheel positions must not exceed 2 mm (normal quality of the wheel control systems and wheel alignment requirement)
XXXXXX XXXXXXX

BMW Genius"

There you have it.

[HighlandPete]

Originally Posted by Assassin

See below:

The take away from BMW's (posted) wheel exchange technical data.

Use BMW approved tires (Star marked) and to BMW OE sizes for the model.

I read that outside of that, we are really on our own.

[mondayze]

Originally Posted by jiimmmayyy

I’ve been on this topic with myself having a set of Supra wheels. I’m xDrive as well and I ran the stock Supra tires and experienced a lot of jerkiness on acceleration. The diameter difference on the stock Supra wheels is about 2%. With like a days worth of AWD research, 1% diameter difference or something close should be okay. I’m planning to run either 235/35 265/30 or 245/35 275/30. Others have ran this on their xDrive staggered 9 wide fronts and 10 wide rears. Sure looks good with spacers on the front though

Use this https://www.tyresizecalculator.com/c...rim-size-chart as a guide. I run a 285/35 on my rear 10.5" wheels and I have seen 275s on the same wheel.

[TBM340]

Hey, do you need a spacer in the front to clear the strut if youre running 255, if so how thich to get the most flush fitment.

[jiimmmayyy]

Originally Posted by TBM340

Hey, do you need a spacer in the front to clear the strut if youre running 255, if so how thich to get the most flush fitment.

I ran 12mm spacers up front. Refer to my pic above