Well, I brought my 545 in for alignment and asked the dealer if the tires made a difference, they said it does not, so I went ahead and aligned. Recently, a mechanic told me it does make a difference, and I should have waited until I got new tires. Who is right?

 

shouldn't be a problem with worn out tires unless it's ridiculous bad. Haven't heard about tires and alignment discussion but I'm using the same theory as when you change your shock or spring, it is recommended that you have an alignment performed because the suspension could be off center now but not because of tires. Heck, if you see tires uneven wear pattern, you're supposed to get an alignment done to fix it, with or without replacing the tires.

Hope that's not too confusing there because I'm not sure if I understand what I'm writing.

 

It all depends on their definition of "makes a difference". Yes tire wear plays into alignment, but it isn't that much. The tires would need to be severely worn to make issue. You will need to realign the new tires though, or you will have uneven wear on them.

 

If you have worn components yes it will make a difference, then again you should be replace the worn component before the alignment.

 

To be more precise with this question, lets say that everything is perfect, nothing needs replaced by the tires. Will the alignment change when the new tires are installed?

My local BMW SA told me that it does not make a difference, so I went thru with the alignment. He led me to believe that the alignment is done in a manner that the tires do not come into play. This was against everything I had ever been taught since a wee pup, but I went along with it because he seemed knowledgeable enough. So I sort of presumed the alignment was performed in a manner that possibly tires didn't even need to be on the car when aligned?

 

No the alignment won't change if everything else is perfect. That is part of the reason why there are turn tables on the rack. Yes I've done alignments before I've done them for 15 years before I broke my back.