Tires replace all 4 or are just 2 OK?

[JCL]

You may still need to replace the front tires, but before you do you could check all four tire pressures. If there is a significant difference front to rear, you could have the same symptoms.

[GSXRliterbikz]

I thought that running diffrent tires front to back could mess up the transfer case on an all wheel drive.

[JCL]

Originally Posted by GSXRliterbikz

I thought that running different tires front to back could mess up the transfer case on an all wheel drive.

The only thing that matters for the transfer case is the rolling diameter. If it is too much of a difference, then yes it can affect the transfer case.

BMW recommends up to 7 psi different front to rear, depending on expected load, so they obviously expect some difference in rolling diameter.

[omodos]

Originally Posted by JCL

The only thing that matters for the transfer case is the rolling diameter. If it is too much of a difference, then yes it can affect the transfer case.

BMW recommends up to 7 psi different front to rear, depending on expected load, so they obviously expect some difference in rolling diameter.

Sorry to revive an old post but been reading what does matter is also tread depth?not just rolling diameter, if you had mismatched tires like I do...varying tread patterns all round, you reckon drivetrain/transfer case failure is something that is imminent and would be immediate or would I get some sort of warning....?

[wpoll]

Originally Posted by omodos

Sorry to revive an old post but been reading what does matter is also tread depth?not just rolling diameter, if you had mismatched tires like I do...varying tread patterns all round, you reckon drivetrain/transfer case failure is something that is imminent and would be immediate or would I get some sort of warning....?

There is no sudden failure - but the clutch packs in the transfer case could wear out prematurely, as they have to slip a lot to allow for the different tyre rolling circumferences.

In extreme cases you will get ABS/DCS errors....

[andrewwynn]

Originally Posted by omodos

Sorry to revive an old post but been reading what does matter is also tread depth?not just rolling diameter, if you had mismatched tires like I do...varying tread patterns all round, you reckon drivetrain/transfer case failure is something that is imminent and would be immediate or would I get some sort of warning....?

Just normal driving around curves will cause enough difference front to back that will likely be more than any tread wear difference. BMW specs a pretty generous 3% i believe allowance front to back rolling circumference difference.

[omodos]

Originally Posted by andrewwynn

Just normal driving around curves will cause enough difference front to back that will likely be more than any tread wear difference. BMW specs a pretty generous 3% i believe allowance front to back rolling circumference difference.

Pretty sure saw it at being like 1% somewhere (not sure someone can chime in?), and having said that no idea how my X has suffered as over the years have often seen the tires wear at differing rates (despite all 4 being the same brand age type etc)


PS just had all four tires replaced same size brand tread etc up front and rear, I didnt get an alignment as had this done soon after my suspension work was done 10 days ago...since then those tires are long gone...do i need to get one done again? someone posted a detailed DIY of how to check if one needs an alignment with the use of threads and pieces of wood etc...who was the poster?