I've not had much luck with the wheels and tyres on either of my 545i Tourings. The first one was always a little vibratory on the motorway until the garage spotted that two of the wheels were cracked, so they never balanced properly and gradually lost pressure. These cars are very sensitive to the pressure being wrong which doesn't help; not only does it upset the suspension but it seems that it messes up the wheel speed sensors and steering angle sensor and confuses the ESP.
By the time I sold the last one I'd had a full set of tyres, a set of new wheels (used the best two to replace the cracked rims, threw away the cracked ones and sold the remaining two) and it drove smoothly. So I was quite pleased that the second 545 drove smoothly at first (on a combo of two Dunlop run-flats, a Goodyear run-flat and a Falken normal tyre; I didn't mess with this until they wore out because it felt fine).
Ever since the complete new set of tyres was fitted last September, two have gradually been losing pressure. So gradual I couldn't get the bead to produce any bubbles when covered in Fairy Liquid, but enough to need topping up 4-5psi every week. Since the car's so sensitive to pressure I didn't even trigger the TPMS warning before knowing I needed to top up so this wasn't too annoying.
But it did need fixing so I bought a set of decent wheels (which happened to come with one pair of good Dunlop run-flats on, pleasing) and on Monday I went to a tyre place to get the wheels swapped over for the decent ones with less corroded edges. I noticed that one of the other tyres was low on pressure - irritating, obviously a puncture. So I had that fixed at the same time.
During this week I've noticed the handling and stability was a bit wayward, which I thought was because the tracking was out. Then this morning the steering was quite heavy turning left, I thought a wheel bearing was failing due to the grumbling, and after a mile or so the TPMS warning came on; I guessed the previously punctured tyre was not repaired properly. And when I stopped to top it up, the pressure was really quite low (surprised the TPMS didn't trigger sooner, to be honest).
Felt fine back at normal pressure but I've got yet another puncture to fix. Why do I have such rotten luck chasing tyre problems on E61s?