Replacing Tyres

[Zakbelle]

I know this may sound like a stupid question but am I supposed to change all 4 tyres a the same time on my E53 X5? Someone at work said I should do so as not to upset the 4x4 settings??

Cheers

Craig

[X5Sport]

It depends upon how worn they all are.  If someone has changed the front and rear pairs at different times then you may find a big difference in the tread depth.

On my E53 version I changed two sets over the seven years and both wore out together so all four had to be changed as a complete set.

There have been incidents recorded of transmission wind up which might have been caused by either different patterns or wildly different tread depths, but it's only a might.  Nothing absolutely conclusive.

Richard

[Zakbelle]

Okay Cheers for that Richard

[Steamyrotter]

I think it may depend on if it is a facelift or not...

Pre facelift you could get away with changing the Fronts or rears (Pair together)  and shouldn't have a problem

Facelift (XDrive transfer box) would probably be safer with all 4 due to the way the transfer box will distribute power.

As the front, rear diffs and transfer box all have a differential operation then in theory it shouldn't matter what you do..
However other items like ABS, 4x4 warnings and even Tyre deflation etc could arise due to difference in wheel speed sensor inputs, even from the smallest of diameter changes.

As mine is a prefacelift with normal transfer box (when it works before someone says!!) i usually just change either front or rear depending which eeds them.. Always have done the pair as they tend to wear the same per axle.
I also have the 20" offset elastic band types fitted to mine so they wear differently anyway..

Current set have lasted almost 3 1/2 years so far and still plenty of meat and tread left

[Zakbelle]

I feel really stupid but what's drive on face lift models? Do you mean the x70?

Cheers

Craig

[X5Sport]

XDrive came in on the 2003+ models (aka facelift) with more powerful engines and 6 speed gearboxes (and some external trim changes).  It uses a variable chain drive unit to alter the drive ratios on the front or rear propshafts and is located within the transfer box.

It's basically a clever variable torque distribution system than can quickly shift varying amounts of torque front to back and vice versa depending upon how the car is being driven, corner forces, wheel slip, power demand, gear selection etc.

All models of the X5 have it after the 2003 changes, plus the E70 and E71(X6) and current F15.  The X6 also has an additional electronically controlled left/right torque distribution system on the rear axle (as does the X5M).

Richard

[Zakbelle]

I'd like to say that all makes sense!

Thanks anyway

Richard how will I know if my car has the webasto system fitted?

[X5Sport]

Look on the right side of the engine bay.  It will be on the right wing as you look into the bay as shown in this piccie (ignore the colour rings which are part of a how to for the breather change).  It's right below the right hand red circle in this picture.  They were fitted as standard and it will say Thermo Top Z.

[Zakbelle]

Oh right, don't remember seeing one of those so maybe I don't have one

Cheers

[X5Sport]

[quote="Zakbelle"]
I'd like to say that all makes sense!
[/quote]

OK it moves the drive away from the slipping wheels to the wheels that aren't so you still have drive on one pair or the other.

R