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Tuesday, July 29, 2014

Doug's Domain

Doug Vetter, ATP/CFI

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May 5, 2005

New Shoes

About a week ago the odometer rolled over 116000, so I decided to take a closer look at my tires. I immediately noticed that the rears had reached the treadwear indicators, which was more or less expected. What I found odd is that the inner portion of the tire had worn more than the outer edges. Normally, such a wear pattern is indicative of a grossly overinflated tire. Truth be told, I'd been running the rears about four pounds on average higher than that recommended for performance reasons, but I didn't expect a few pounds to make that big a difference.

I decided to do some research on the tire and found a couple similar experiences online. Those people attributed the wear pattern to the different compounds used in the tire's construction. Apparently, the inner portion of the tire uses a softer compound for better snow and rain handling while the outer edge is harder for better holdup under cornering conditions. So, what actually causes the wear pattern? I don't know. Perhaps its a combination of tire pressure AND construction. No matter, really. At 29000 miles, it was time for new shoes.

Given my favorable experience with Tirerack, I decided to go directly to their website. I quickly found the Pilot Sport A/S 225/50/YR16 at $155 each, or $650 shipped. The last time I paid $750 shipped, so I figured I'd go ahead and buy from them again. Before I placed the order I called my dealer's parts department to ask if I could ship the tires directly to them -- just as I did with the last set. Predictably, they said "No problem, Doug!", so I called Tirerack and placed the order. They had all my info from the last order, so it took less than a minute for the rep to check stock, take my payment info, confirm the billing/shipping addresses, and give me an order confirmation number. Kudos to my dealer's parts department for providing a convenient drop point, and to Tirerack for making the entire purchase experience very fast and completely painless. This is how business should be done.

(Image: Pilot Sport A/S 225/50/YR16)Even though I knew Tirerack had a warehouse less than 150 miles away, given that I didn't request expedited shipping I was still surprised to see the tires arrive at my dealer exactly 24 hours later. I had ordered them a bit early just to make sure they'd arrive before my maintenance appointment early next week, but I honestly didn't expect them so soon. You can see from the picture how they're shipped.

Given the money I saved on the tires, I figured I'd go ahead and replace the control arm mounts as recommended by my mechanic. While I was at the dealer to take that picture, I put my name on a set of two mounts they had in stock so we can replace them while we have the tires off the car.

Defective Clearcoat on Rim

The one downside to my close look around the car is that I found a small, but noticeable defect in the clear of the rim that the body shop installed during last year's repainting binge. It looked as if a bubble had formed in the clear and that the bubble fractured, leaving a round gap in the clear protective finish. Fearing that this small defect would degenerate into a a greater loss of clear in the coming months, I brought this to the attention of the parts department.

They told me that in order to process the claim, they'd need to take a digital picture of the defect and send it to BMW-NA headquarters, so they took care of that while I discussed some things with my mechanic. The goal is to have a replacement rim installed at the same time I'm swapping tires, but if I need to do this later, so be it.

Transmission Status

It looks as though the throttle position sensor did nothing to change the 1->2 shift characteristics, but for what it's worth, I haven't experienced the pendulum shifting problem since we replaced the sensor. I am now contemplating starting a warranty claim on the transmission, but I fear that the problem will be too subtle to justify a replacement. Guess we'll have to wait and see.

Parts $650, Labor $0, Total $650. Total Mileage 116025.

May 10, 2005

Yesterday I got a call from the parts department with news that not only had the dealer's service manager agreed to replace the defective rim, the rim had arrived in inventory -- just in time for my appointment today.

(Image: Control Arm Bushings)The road force numbers were slightly better (lower) than last time. One tire was less than 2 lbs (effectively perfect), while the others were 4, 7 and (gulp) 14. However, the highest reading was due to a very slightly out-of-round rim, not the tire itself. The problem rim was on the right front, but my mechanic moved it to the right rear in an effort to reduce its effects. Frankly, I didn't feel it when it was on the front, and following some driving, I can't feel any vibration with it mounted on the rear either.

Thankfully, the rhythmic noise coming from the front end is gone (it was indeed a result of tire wear) and the steering is a bit more more neutral -- not that the old tires tramlined to any significant extent. The steering also feels a bit more "insulated" than it did previously, but that may have something to do with the new control arm mounts.

It may be hard to see from the picture, but my old mounts had started to crack (and one was cracked nearly half-way through), so my mechanic's advice turned out to be correct. If you're wondering when you should replace your mounts, I think it has a lot to do with your driving habits and/or the number of potholes you've cursed, but 100K indeed seems to be a good point to replace them. As usual, the labor cost isn't cheap, but the mounts themselves are reasonably priced -- especially given how long they last.

Fortunately, I can at classify a bulk of the expenses on this latest maintenance binge as "scheduled" or "routine". Tires wear out, and there's nothing much you can do about that, short of not driving the car...and to a BMW owner, 'dems fightin' woids!

Labor: $427, Parts $30, Total $485, Total Mileage: 116193.