Is it safe to run the oversized staggered wheels

[mejim707]

With my recent debacle after replacing the transmission and having a very nasty shudder / shake / jerking form a few weeks following, I brought my car to BMW who diagnosed that the transfer case front wheel drive chain was worn out and had a lot of slack in it causing the issue.

They told me that running larger wheels and tires was why this happened. However, I'm running the sizes that BMW suggests are ok for my car.

Fronts: 275/40/20
Rears: 315/35/20

I didn't think this would be an issue since it adheres to BMW suggested sizes but the master tech told me only the M series X5s can run these size tires because of the programming of the computer. They also quoted $8500 to replace the transfer case which seems like a fair and reasonable price and not at all a laughable quote lol

So, is it safe to run this staggered setup on an X5 that is not an M package?

[crystalworks]

Yes. Not sure why the tech would tell you that. Tens of thousands of non M x5s are running that setup every day. Including 2 of mine.

Not sure why your transfer case failed, but assuming your tires were evenly worn on those 20's, they weren't the cause.

[mejim707]

Originally Posted by crystalworks

Yes. Not sure why the tech would tell you that. Tens of thousands of non M x5s are running that setup every day. Including 2 of mine.

Not sure why your transfer case failed, but assuming your tires were evenly worn on those 20's, they weren't the cause.

That's what I thought, but the "Master Tech" was so adamant about it I couldn't say much. I said I used the exact sizes and pressures recommended for this year X5 from BMW. I pointed to the wheels and said "275/4020 up front and 315/35/20 in the rear, it's the common staggered setup." He said "it's not what's in your door. Go home and put the 18s back on. Running oversized tires is why your case failed."

This did not seem right, but I'm no master tech. I just know what I've learned and I've been running these wheels for many years without issue. The tires are also all brand new.

To me I think it was just time. The case has 265k on it now, and I think that the 2-3 shudder I was experiencing for so long may have started the case chain to start it's descent into oblivion.

The way the case was bouncing around in there and the ratcheting / loose chain sound coming from it was clear the case was no good. If I had a lift I could have figured that out in about 5 minutes but I have no lift. I need to change that.

I am thankful they diagnosed the issue and didn't charge me for the visit though. That's was cool of them.

[crystalworks]

Hah! Buy the sticker for the 20's and put it on the truck. It's got a part number and is affixed based on the x5's build. Wonder what his answer would have been if you'd had the sticker for 20's.

I think it was just age and damage as you said. Parts wear out and @ your mileage not an unknown failure.

[ard]

The tech is an idiot.


"I understand you need to hew to the party line, and thats fine- but from a technical basis, those tires have a 'mismatch' of 0.00000mm in diameter and rotational variation, front to rear. Same as 18s. They CANNOT be the cause."


But thanks for playing.


Having said this, unless you are the original owner, knowing what prior owners did can be hard to know.


Sounds like you are getting it sorted for a bit less than $8500. lol




Edit...there is no 'setting' or coding feature to 'set tire sizes'. This proves that there is only ONE tire size for every E70. Namely ONE 'outer diameter'...all different size tires with lots of numbers, but the rolling diameter on all BMW tire choices are the same!

[mejim707]

Originally Posted by ard

The tech is an idiot.


"I understand you need to hew to the party line, and thats fine- but from a technical basis, those tires have a 'mismatch' of 0.00000mm in diameter and rotational variation, front to rear. Same as 18s. They CANNOT be the cause."


But thanks for playing.


Having said this, unless you are the original owner, knowing what prior owners did can be hard to know.


Sounds like you are getting it sorters for a bit less than $8500. lol




Edit...there is no 'setting' or coding feature to 'set tire sizes'. This proves that there is only ONE tire size for every E70. Namely ONE 'outer diameter'...all different size tires with lots of numbers, but the rolling diameter on all BMW tire choices are the same!

Well that settles it then. The "Master Tech" flat out said the "oversized wheels are only meant for the M series" and shouldn't be run on other X5s. If there's no programming to incorporate tire size, this shows he was in fact either misinformed from his master training, or he was being less than honest.

So, I'll just keep running these wheels and tires and not even concern myself with it any longer. This case is old, and at least it failed around the same time as the transmission. Like I said earlier the trans was replaced due to an apparent 2-3 shudder.

But after the trans replacement was complete I generated a shudder they said was from the new torque converter but that was likely the transfer case instead. Not sure to be honest, but it did fail soon after the trans and torque converter replacements.

All in all, tomorrow morning the new case goes in. This should be the end of the long saga.

For anyone interested, transfer cases are inexpensive. You can find low milage ones for about $250 - $500 depending on the miles. The install is also very easy if you have a lift or can get the car up high enough that you're not squeezing under it.

So if you ever have a feeling of a shake across all driving conditions that becomes a jerking feeling at higher speeds and a heavy shake in neutral or when coasting and braking, chances are your case chain is worn causing too much slack driving your front diff / wheels. Sometimes a failed axel could cause this, but it's likely the case.

[SF2000x5]

Would you consider xdelete for “rwd”? I wonder if this would get rid of the shudder.