XSeries-forum

I am wondering if anyone can give me some advice as its driving me mad!

Basically I have had the X5 about 6 months now and everything is fine with it apart from an issue I get which I am wondering is tyre related.

I have the 20 inch staggered rims 315 35 20 on the back 275 40 20 on the front and when I originally bought the car it had a set of Achilles tyres on the back with about 3mm and a set of Goldway tyres on the front with about 5/6mm. The car drove fine and I didn’t notice any issues.

I decided to replace the rears for a set of Pirellis 315 35 20 as they were a little worn on the inside. Almost immediately the car drove differently...going up hills it had no power…going over bumps the steering wheel would lock/stiffen up as if it was driving on the snow etc…the gears would shift at the wrong times…there was like a grinding/whining noise…generally the car wasn’t happy!

I spoke to the tyre fitter and he said to match up the tyres so as a cheap option/test I had x4 accelera iota tyres fitted and the car drove better (although not perfect).

I took the car to an indy who checked the codes and found nothing wrong except the glow plugs and control unit which I have had swapped (as well as a new breather and air filter).

This has made a difference and the car seems to want to pull quicker but there is still an issue which I think has to be tyre related. I still get a grinding/whining noise, the power is not great going up hills (and Sheffield has a lot of hills!) and it actually feels like I am towing something. The stiff steering/locking still happens when going over a pot hole or bump etc too. Driving on flat decent surfaced roads it is generally fine and changes gears etc without any problems.

I am thinking of spending a few couple of hundred on a set of 4 matching part worn * marked tyres but do people think this is likely to solve the problems? I do not want to spend £700+ on 4 new * marked tyres for it to still be there 

Sounds like the diff but then that wouldn't have an effect on the steering. What tyre pressures are u running? A mixed set of tyres previously sounds like trouble

I'm punting in the dark here but is yours the later e53 with the electric transfer box gubbins in it ???
theyre known for bits breaking and you can get a kit to fix it fairly cheaply

cant see tyres causing the symptoms your describing tbh unless the tracking was a million miles out 

yeh im worried its the diff or maybe transfer box  ive tried 32 and 34 psi in all 4 but it still happens. currently ive got them at 32

its a 56 plate le mans blue

You can pul a fuse ( number 46 ) to help eliminate certain transfer box problems. I believe need our resident transfer box man ( KKX5 ) to tell you how to go about it.
There's been a few reports of diff failures posted up recently, use the search button to see if the symptoms sound similar.

Yep, fuse 46 out...+ I'm tired of the tyres on this forum Bmw approved on all xdrive ( 2004+ ) staggered set up bmw's...

As above....,and change them as a set.  If you have nasty noises there is a very good chance it is tyre related and a wide tread depth variance is asking for trouble.  We have had owners report similar in the past and changing tyres cured it.

These cars are sensitive to tyre type and tread depth.  Cheap tyres means increased risk of broken diff/transfer box.  Never put el Cheapo tyres on 2-tonnes of car.  It is a false economy except on agricultural pickups.

Thanks guys, I will try pulling out the fuse tomorrow - is this just a straight pull out - drive it - put it back in job? I can clear any codes with my scanner if needed.

I'll also get a set of * marked tyres on too

Leave the fuse out and test drive the car, see if there is any difference.

Drove it with the fuse out and its like a different car, drives perfect, no whining, no grinding and fine over bumps in the road etc...

Would you recommend the next step be tyres and if not then get the transfer box looked at? Or the other way round?

transfer box first then tyres

[quote="ianst0028"]
transfer box first then tyres
[/quote]

+1

I was hoping I might get away with just the tyres 

[quote="dani_armo"]
I was hoping I might get away with just the tyres 
[/quote]

Probably the odd tyres that's done the damage!

Forgive my ignorance here but what have we just proved. What does removing F46 do. Turn it into 2 wheel drive or what. Stop drive going to the transfer box???