Rear tires worn on inside; Should all 4 be replaced?
 

I was at Discount Tire getting a quote to replace my 315/35R20 rear tires as they wore out on the inside after 23K. I was told that they require all four to be replaced as the all-wheel drives need the same wheel diameter on all four. I didn't realize that the all wheel system was this sensitive. He went on to add that Discount Tire has seen Mercedes GL Series, Subarus and an X3 have issues with mismatched (new vs used) tires. Not sure to the truth of this. My front tires have more than 60% left.

Any thoughts or opinions?

If you have 60% left on your front wheels I think you will be fine. There are issues related to different rolling circumferences front and rear, and there is a spec for it. I would leave your fronts myself if they are original size and you are putting the original size again on the rear.

Edit: Just checked the profile of the OP. It is a 2001 X5, so pre x-drive. I would worry even less with a 2001-2003 model than with a 2004+ x-drive model.

Get your rears and a much needed alignment

:iagree:
I was in the same situation a couple of years ago, I replaced the rears only with the same size tire and the fronts were 60% or so. Now after 15K miles, no problems at all. :thumbup:

be sure to get alignment at some place that knows how to do BMW alignment, ie, placing weights on the seats & rear - otherwise you will end up continuing to buy tires - I got well over 35k on my Diamaris with dead even wear across all 4 tires, so it can be done - granted, alot of those miles were on the interstate, but I still had identical wear on all 4.

do they have to use weights? I never had mine done with weights
:dunno: just curious to know if it makes that much diff. idk?

I've heard a couple of people dismount the rear tires and reverse, since the outside thread practically brand new due to agressive negative camber setting on X5, Anybody done this as well?

Never done it cause by the time I wear the tires they are kinda old (base on age) so I just replace them.

While it is technically possible, you would be putting worn tires on that have worn in a different manner. Tires take a set from running in a certain position on the vehicle, and that is why BMW recommends not moving them to other positions on the vehicle. Handling will be compromised. If you don't mind the reduction in handling, it is a cheap bandaid solution. I have always worked on the premise that the vehicle has a lot of design and engineering features to improve the handling, and throwing that away is a waste.

Thanks for all inputs and suggestions! I had the alignment done and the shop could not correct the camber anymore. It sits very negative. The right rear has bad outer toe ... pointing away from the vahicle too which they cpuld not fix either. They think I might need to start off by replacing control arm, bushings etc.

Sounds right, shop was able to get mine down to -1.7 deg which is much better than it was but also told me could not go anymore due to a caster issue related to possible worn/wearing control arm/bushings. 23K is pretty good out of the rears from what I was used to (14-15K).

Regarding the swap of rear tires from rim to rim to wear the other sides of the tires, don't most directional tires have an ugly side and a pretty side (speaking of the sidewall)?