Just had to replace all 4 tyres on my 525 after 20,000 miles. It is
fitted with Dunlop Sport 18" runflats and it cost me £740 to replace
them - works out at 3.6p per mile!

The local dealer says this is normal (the inside of the front tyres
were bald) - geometry tests showed everthing in alignment.

I asked the dealer if I could replace the wheels with another size and
with less expensive tyres - they could not say! Anybody out there have
any ideas?

20k on a tyre is not too bad.  £740 for 4 is expensive.

On BMW's the rears tend to wear in the middle (even if inflated correctly)
and the fronts (especially the NHS (left) in the UK (roundabouts)) on the
outside edge.  Wearing on the inside edge is indicative of incorrect
alignment.

On BMW's the rears tend to wear fastest, so when they get low in the middle
put them on the front where they will go fastest on the edges and put new
ones on the edge.

If the fronts wear very asymmetrically you can turn them one the rim (if
reversible) or turn them on the rim and swap sides (if not), but I would
look for a geometry fault first.

Found this menu of wheels on the web.
http://www.e60.net/information/options/wheels/

Just had to replace all 4 tyres on my 525 after 20,000 miles. It is
fitted with Dunlop Sport 18" runflats and it cost me £740 to replace
them - works out at 3.6p per mile!

The local dealer says this is normal (the inside of the front tyres
were bald) - geometry tests showed everthing in alignment.

I asked the dealer if I could replace the wheels with another size and
with less expensive tyres - they could not say! Anybody out there have
any ideas?