[del330]

Firstly, hello everyone. I am a very new F31 owner having purchased a 15 plate 330d xdrive M-Sport car a few weeks ago which i'm over the moon with, especially after coming from an E46!

Anyway, when I bought the car it had non-runflat winter tyres on and the fronts had a bulge in the sidewall, so I straight away swapped them for some Conti Sport Contact 6's. I intend to swap the rears over next month too to the same tyre. I have the 19" staggered 403 rims.

However, I have since read about issues with the transfer box when not fitted the approved BMW run-flat tyres and now I'm bricking it!!!

The car seems to drive fine at the moment, but what are the sypmtoms of damage to the transfer box from running the wrong tyres? What should I be looking out for? And also, do you think I'll be ok with a full fresh set of Conti'l all round?

I'd love to hear your opinions...

Cheers,

Del

[teaston]

The star marked tyres are just a marketing thing, as long as you fit the correct sizes then you'll definitely be fine.

[UKF30]

Originally Posted by teaston

The star marked tyres are just a marketing thing, as long as you fit the correct sizes then you'll definitely be fine.

What about Warranty , will Dealer say anything ??

someone said warranty void if not star rated Tyres which made me worry since then

[del330]

Hi, thanks for your response, that reassures me a bit. Maybe a few other will be able to share the same opinion!

Have you been running non-runflats on your 335d?

[teaston]

Originally Posted by del330

Hi, thanks for your response, that reassures me a bit. Maybe a few other will be able to share the same opinion!

Have you been running non-runflats on your 335d?

Yes, MPSS then PS4's and now Goodyear Assymetric 3's, dealer's never mentioned them on the many occasions the car has been in with them.

[fat dog]

I've been running MPS4S tyres all round on my 435d x-drive for 8 months now and the car seems absolutely fine with the set up. I keep a very careful eye on pressures and tread depths but have no concerns myself. You're possibly more likely to suffer issues if you mix different tyres or different tread depths on the same car. But then again, I've had an x-drive courtesy car from a dealer that had 3 x pretty worn tyres and 1 x brand new tyre (presumably due to a puncture) which they obviously felt was fine.

HighlandPete posted a few interesting comments and some good insight into star marked tyres a few weeks back. Do a search from the last few weeks, as it might help with your decision.

[330Stevie]

Originally Posted by teaston

Yes, MPSS then PS4's and now Goodyear Assymetric 3's, dealer's never mentioned them on the many occasions the car has been in with them.

But it’s never been in with transfer box issues?

[teaston]

Originally Posted by 330Stevie

But it's never been in with transfer box issues?

No 57K and going strong

[Alscoob]

Don't know about BMW, but on my previous Merc I had Conti's and used MO marked tyres, the tread was very slightly different to a non MO marked tyre of the same brand and type. I was told (true or not) by a tyre guru that the MO tyre was made to compliment the car which could mean different tread and compound mixtures.

Guess the same applies to star marked tyres for BMW, but I have used non runflat winters, RF summers & Non RF summers and the best by far or summer is the latter.

I believe the most critical thing with X drive as most other 4x4 systems is to have matched tyres and be aware of tyre tread depth between front and rear. A 3mm rear tyre and 8mm front tyre rotate at different rates in this case, the front much slower than the rear which could wind up the centre diff / transfer box. Guess a simple question to the dealer would tell you what the limits in tread differential should be.

Anyway, welcome to this place and enjoy your car.

[del330]

Thanks guys, that does put my mind at rest!

fat dog - out of interest what pressure have you been running, I'm currently running around 35 all round. I'll check that thread out too, thanks!

Thanks Alscoob, I think I'll get the rears changed to the same as the front asap, they'll then all be same tyre with equal tread depths and I'll keep an eye on tyre pressures.

[lethbridge]

I've always kept with run flats but I have never worried about whether I use star marked or not. I think your question is about use of approved tyres in general as opposed to runflats. My F34 GT tyres are a size bigger than the other F3Xs and are hard to get especially if you want a * marked matching set front to rear (i.e. typically only Pirelli & Conti & I'm not a fan of either). I end up running a different brand front to rear (Goodyears & Dunlops - only the Dunlops on the front are * marked).

I've done 65k in 3 years with no issues & plan to keep the car until around 100k and I wouldn't expect any or worry about it at all. Yes it does give BMW an excuse to wriggle out of a warranty repair but I'd like to see the proof that the issue was actually caused by the tyres and I'd be surprised if they tried to avoid paying out. If you are running the wrong size tyres front to rear which causes a difference in rolling circumference front to rear then I'm sure the box would complain and they would not view a warranty job kindly...

At the end of the day common sense says they have to allow for full tread on front, minimum tread on rear which would be a bigger tolerance difference than tyres the same size that are star marked or not, runflat or not... I know there is a lot of technical stuff on this but we're not expected to know all that in making tyre choices...

[HighlandPete]

Originally Posted by Alscoob

Don't know about BMW, but on my previous Merc I had Conti's and used MO marked tyres, the tread was very slightly different to a non MO marked tyre of the same brand and type. I was told (true or not) by a tyre guru that the MO tyre was made to compliment the car which could mean different tread and compound mixtures.

Guess the same applies to star marked tyres for BMW, but I have used non runflat winters, RF summers & Non RF summers and the best by far or summer is the latter.

You are correct on Merc and MO tyres, same for other manufacturer's approved tyres, including BMW, Porsche, etc. Merc clearly state in their technical data that MO tyres can be different sizing, different compounds and specified with different performance characteristics. That translates to 'different' than the generic equivalent, the approved tyres may not be the same as generic tyres of the same size. They may not even have the same RC.

Using non approved tyres on xDrive, you take a risk. May be a small risk as many compatible tyres will work and keep in tolerance, but there are no guarantees with non approved tyres.

[ryanwarriors9]

Originally Posted by fat dog

I've been running MPS4S tyres all round on my 435d x-drive for 8 months now and the car seems absolutely fine with the set up. I keep a very careful eye on pressures and tread depths but have no concerns myself. You're possibly more likely to suffer issues if you mix different tyres or different tread depths on the same car. But then again, I've had an x-drive courtesy car from a dealer that had 3 x pretty worn tyres and 1 x brand new tyre (presumably due to a puncture) which they obviously felt was fine.

HighlandPete posted a few interesting comments and some good insight into star marked tyres a few weeks back. Do a search from the last few weeks, as it might help with your decision.

What pressures you running mate?

[RickLS7]

I also have a Boxster, there aren't many N rated tyres available in my size so I've had Goodyear Eagle AS2's fitted the last couple of times. Every time I try and buy more, take the car in for a service or whatever I have mechanics rushing to tell me they aren't N rated like I'm going to die driving with them on.

It's a Boxster ffs, not a 911 turbo or GT3. Maybe if Porsche spent a bit more time testing, there would be a choice rather than just Michelin PS2's where the rears run out in just 6000 miles (got 16,000 out of the AS2's which are equally capable).

[del330]

Thanks for the further input guys, all very helpful information.

Originally Posted by lethbridge

At the end of the day common sense says they have to allow for full tread on front, minimum tread on rear which would be a bigger tolerance difference than tyres the same size that are star marked or not, runflat or not... I know there is a lot of technical stuff on this but we're not expected to know all that in making tyre choices...

Lethbridge, you make a very good point, have approved tyres with full tread one end and low tread the other end has got to be a bigger difference than any combo of new tyres all around in the correct size!

I have actually emailed BMW UK now to ask if I am ok to fit Conti SP6's as opposed to runflats, so it'll be interesting to see what they come back with....

[HighlandPete]

Originally Posted by RickLS7

I also have a Boxster, there aren't many N rated tyres available in my size so I've had Goodyear Eagle AS2's fitted the last couple of times. Every time I try and buy more, take the car in for a service or whatever I have mechanics rushing to tell me they aren't N rated like I'm going to die driving with them on.

It's a Boxster ffs, not a 911 turbo or GT3. Maybe if Porsche spent a bit more time testing, there would be a choice rather than just Michelin PS2's where the rears run out in just 6000 miles (got 16,000 out of the AS2's which are equally capable).

British Tyre Manufacturers’ Association

Vehicle Specific Tyres
Vehicles homologated on specific tyres should have the equivalent replacements fitted when they require changing.
Specific tyres for a specific vehicle (and marked accordingly) are possible. It is recommended to follow the vehicle handbook guidelines closely (or seek assistance from vehicle or tyre manufacturers) when changing these.

Examples are possible where one could deviate from those marked and others where that is not recommended –

e.g.

1) MO marking for Mercedes. It is possible to fit non-MO marked (and could use MO marked for another vehicle)

2) N-marked tyres for Porsche. Due to the particular characteristics of their vehicles, Porsches must take the correct N-marked fitments. It is also recommended that N-marked tyres are not used on any other vehicles.

Others versions exist in the main for performance/prestigious vehicles such as Porsche, Chrysler, Ferrari, Mercedes AMG, Audi, Bentley, BMW and others.

NB: Other countries may have different laws regarding the replacement of Original Fitment tyres.

If in doubt, always contact your vehicle or tyre manufacturer for advice.

Interesting that the Porsche 'N' tyres are in a separate category, for exact fitment, and not for other vehicles.

[HighlandPete]

Originally Posted by del330

Lethbridge, you make a very good point, have approved tyres with full tread one end and low tread the other end has got to be a bigger difference than any combo of new tyres all around in the correct size!

I have actually emailed BMW UK now to ask if I am ok to fit Conti SP6's as opposed to runflats, so it'll be interesting to see what they come back with....

BMW normally work within the 3mm rule, as do many other AWD manufacturers. Well documented and why dealers (usually those with actual experience) will make recommendations which keep tolerances in the 1% range.

[fat dog]

Originally Posted by ryanwarriors9

What pressures you running mate?

I'm running 36.5 psi all round.

To add a little more food for thought, my car had a free visual health check while it was in the dealer for another matter on Friday. The report notes 'non-approved tyres fitted' to the front. For the rear tyres, the report states 'tyre size not on file'.

Any warranty claims on the drive train from now might be interesting...

[del330]

Originally Posted by fat dog

I'm running 36.5 psi all round.

To add a little more food for thought, my car had a free visual health check while it was in the dealer for another matter on Friday. The report notes 'non-approved tyres fitted' to the front. For the rear tyres, the report states 'tyre size not on file'.

Any warranty claims on the drive train from now might be interesting...

Hmmmmmm, interesting! Would it be worth asking them if it's a problem with warranty? I am still awaiting a response from BMW UK......

[fat dog]

Originally Posted by del330

...Would it be worth asking them if it's a problem with warranty?

Well, the car is back with the dealer in a couple of weeks for wheel replacements under warranty. As they'll be taking the tyres of the old wheels and onto the new ones, seems a good time to broach the subject.

[HighlandPete]

Originally Posted by fat dog

Any warranty claims on the drive train from now might be interesting...

The following is the sort of info available on newTIS: Includes the 335d

36 12 ...Notes regarding tyre/wheel exchange

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; if mixed tyres are fitted, different tyre sizes are permissible.
• 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)

Your wheel and tyre info is logged, garage is covering its position, to say the least.

[tjlees]

Always been the case with AWD that you have to keep the front and back axle within about 2mm (2/32 inch?) for me

Putting on new rears at 8mm with the front less than 6mm, means the fronts will have to turn faster than the rears, which will put additional stress on the transmission and can/will damage it over time/mileage. Even one new tyre v others that are less than 6mm will cause the diffs to work overtime thus opening your transmission to damage. may even confuse your DSC

A puncture may result in all 4 wheel needing to be replaced, which I had to do on my last AWD car given that all tyres were at 3mm.

I can understand Porsche and bmw specifying approved tyres only. Not withstanding the performance aspects, the manufacturing variances in diameter may mean the 2mm difference advise does not hold true - again leading to transmission damage overtime, if there is a difference in tread