Tire Wear Patterns and Rotation

I'm running Michelin Pilot Sport AS Plus tires on the front (good tread) and Kuhmo's (nearly worn out) on the back. 235/45-17 all around. This is how I bought the car. The rears need to be replaced soon (about 3/32 [2.5 mm] tread left, just above the wear bars).

I was at Costco yesterday and saw a sign from Michelin suggesting that if you replace two tires, they should go on the back axle. Their rationale is that you want the deeper tread and better hydroplaning resistance on the back axle.

I always thought you'd want the better tires on the front, because if you loose steering, nothing else matters.

I also noticed that in the BMW owner's manual it suggests *not* rotating the tires.

I'm looking for some experienced E39 opinions on this. Which tires wear faster, front or back axle? Are the wear patterns even enough that rotation is not needed?

Also, any opinions as to the choice between Michelin Pilot Sport PS2 (summer) and Pilot Sport AS Plus (all-weather)?

personally i would buy 4 new tires of the same make/model and use the 2 current fronts as spares

Actually, a lot of stuff matters more than steering. Braking, for instance. Having the steering wheels at the end of the car that's going forward instead of at the rear.

Sliding friction is lower than static friction. Therefore, the end of the car that's sliding will go faster than the end that's not. If your rear tires slide, you swap ends and go butt-first wherever you're going to end up. If your front tires slide, you at least continue to point the direction you were going and you can slow down to regain traction.

The good tires always go on the back, even with FWD.

I make it a habit to never buy just 2 tires. I replace all four when wear becomes apparent (winter as well as summer treads). I also don't rotate for a number of reasons but running staggered in summer is part of the reason but winter tires don't lend themselves well to rotation either as they are (of course) directional....Wish Roundel would do a tire performance review like they used to back in the 70s and 80s. I haven't seen one in since returning after about a 10 year hiatus as a member.

BTW: Would be surprised to learn that Costco has a wide choice of tire options for a bimmerphile. Would anticipate that they tend to stock most popular "standard" options.

Yours may be. Most are not.

Tire Rack has pretty much preempted that for most enthusiasts. While they only test and review (and compile customer feedback for) tires that they sell, that leaves out very few (Nokian being one notable exception). Their tests are usually better than ROUNDEL's simply because they have the resources available to do it better. That, and they do it more often than ROUNDEL is able.

I don't find the Tire Rack info credible. I believe it to be primarily a popularity contest...a reflection of sales more than of discriminating road testing. While some of us will be objective when we complete a Tire Rack questionaire, I think many will say mostly positive things about the tires they purchased to justify what they bought. Then too, how many of these votes are based on a well rounded background of alternatives?

Back in the early 80s I remember nicely conducted tire road tests done on 3-5 and 7 Series cars all. The tires weren't just assigned a number rating either we could get some articulate descriptions of handling, wear and noise done by true Bimmerphiles. I contrast that to Tire Racks popularity contests as a collection of unqualified opinions from a wide range of expertise levels on a wide variety of marques. I loved the purity of the Roundel tests in those days.....BMW cars only were considered as well it should be.

I sincerely think a revisit would be well worth the effort especially with all the driving schools we have now to draw that information from. A merger of interests between those of manufacturers like Michellin, Pirelli and Bridgestone with those conducting the Drivers Schools could generate some VERY useful information. Wish we could see this happen.....It's the kind of information that many of us subscribe to Roundel for and doing so underscores the enthusiast that BMW owners represent versus lesser marques.

The Tire Rack database is huge, so I really find the "Survey Results" useful. There are distinct result differences indicated in the "Survey Results" for niche factors such as "Noise Comfort", which is important to me since I have a convertible.

When I phone them for opinions, every person I've spoken with has personally driven on a lot of tires and can justify their recommendations. The reviews that Tire Rack posts on their website are done by staff who drive, drive and drive on the private Tire Rack track. Those reviews seem like exactly what you are longing for (eg. http://www.tirerack.com/tires/tests/testDisplay.jsp?ttid=118). Note that they used a BMW 2009 328i Coupe for testing of the various tires in that survey. Another benefit is that a Tire Rack review can be a cold analytical report; a magazine review must also be entertaining for a general audience.

... I'm "defending" Tire Rack, because I like them a lot. If I worry about anything, it is that they so dominate the market, that they maybe starting to squash competition. Pretty much all the local tire shops in my area now take delivery of Tire Rack tires.

I agree with you in regard to the technicians on the phone.....They are good and put a lot of effort into sampling the tires and various cars. However, I was speaking to the Online Tire Rack Tire ratings which are produced from sampling the buying public not the technicians at Tire Rack. I've used them for many years but would still prefer tire reviews done by BMWCCA for BMW models. I do think it odd that I feel a consistent push to Dunlop Tires by the technicians from Tire Rack and the one time I had Dunlops I absolutely hated them.

As for appealing to a wider audience.....why should we as BMWCCA members care? We have what is considered by many in the industry as the best club mag and it is created specifically for BMW enthusiasts. Anything that attempts to serve a wider audience does so at the risk of diluting effectiveness that specialization affords. It really is already quite a challenging task to address all the models of BMWs produced at this point. Would prefer the focused specialization for rating tires for each model of our favorite marque.

I just meant the various kinds of readers of any car magazine (including Roundel) (e.g. track rats, detailers, poseurs, Walter Mittys, etc)

Ya I know .....Since we are on the BMW CCA website I'm strictly speaking from a BMW enthusiast point of view.