Replaced Tyres - Now DSC & 4X4 Off

[Jughead028]

Hi All,

I just replaced the tyres on the X5 E70 I just bought, and now the DSC and 4X4 are coming up with errors.

The tyres I bought were

235/55 R19 front
and 285/45 R19 rear.

After fitting them I found out the fronts should be 255/50 R19s.

Would this make enough difference to the DSC system to throw an error?

When I bought the car, it had 235/55 on the front, and on the back it had odd tyres - 285/24 on one side and 255/50 on the other!

There is a .2% difference between the diameter and circumference of the two tyres.

DSC & 4X4 were fine before the tyre change.

Cheers,

JG

[andrewwynn]

Your math is correct. The problem is not from tires size unless you have a huge psi difference.

What codes are active?

[Jughead028]

Didn't check the codes, but did find the reason.

Yer, PSI difference.

Front - one side 44 PSI, the other 38 PSI.

Back - one side 40 PSI, the other 44 PSI.

Evened them out to 40 PSI and no more problem.


Thanks for the help.

Now just have to get the right pressure and all good.

[andrewwynn]

Wife's e70 spec is 33 front 41 rear but she has 3rd row. E53 is spec 32 everywhere unless the back is full of tools then spec is 39 rear.

I would start with spec and modify based on wear.