Silver Bullet here. We spoke today on the phone from Calgary.
Here's what a local supplier said about a square set up (I assume that means same fitting on all 4 wheels, as opposed to rear wheels wider than front) for winter tires, as recommended by my BMW dealer:
"Not trying to pull a dirty sales tactic or anything on you, but BMW is giving some fairly bad advice. I’ve been playing around with a fitment calculator and the best sizing I can come up with for a square fitment is 245/40R18 for the front and 245/45R18 for the rear and even then it is about half an inch off the recommended height on the rear tire. For the 235/40/18 fitment all around, it would be nearly 1.5 inches off recommended on the rear. BMW was doing the incorrect fitment for their vehicles last year as well.
I’ve called around to a few of our tire suppliers as well as some local tire shops as well and they are all recommending the staggered fitment for the new M3s."
It seems that you (Tire Rack) are also recommending a staggered setup.
What do you think of that?
Why would BMW recommend a square setup? What problem can arise by not having the wider rear tires?
Last edited by Projectile; 10-07-2009 at 08:56 PM.