Tires: 2005 Focus rear tire wear and vibration, Tire Vibration, Tire Wear

Question
HI, I have a 2005 Focus with 130,000 Km.  I am on my 5th set of tires and I think I need a another set.  The rear tires come out of balance quickly when driven at 120 kph.  For example, I drove 2040km over three days after having the tires balanced at 100 to 140 kph.  After 1000 km some vibration was apparent.  By the end of the trip the vibration was as bad as when I took the car in for balancing.  I took it to the dealer where I bought it 3 times for this and poor fuel milage.  He first told me there was mud in the wheels ( < 5000 Km), then the tires were worn out (40,000Km) I replaced the tires and by 50,000 Km they were vibrating again.  I had them rebalaced after removing the wheels and washing any dirt out.  I also picked out any pebbles stuck in the tire tread.  They were vibrating again by 60,000 Km.  I took the car to the dealer again and was told the tires were defective.  I replaced the them with a different brand which started to vibrate again by 80,000 Km.  I went to a different dealer and they did a 4 wheel alignment. They could not get the right rear wheel to come into correct alignment unless they replaced a suspension component. (Chamber not quite right but it was close)  I was told the problem would be solved by this but I needed to replace the tires again.  I did replace the tires and this time they stayed pretty good for about 15,000 Km. Fuel milage numbers went up by about 7% after the wheel alignment. Now they are vibrating again.  The right rear tire looks worn ( this is the wheel that they could not completely adjust) while the rest are in good shape.  I think the wheel alignment is still not right and the rear suspension has been wrong from day one.  Is this a common problem with the Focus?  The dealers I spoke to claimed it was unusual. Is there anything that can cause the wheels to go out of balance other than misalignment?   
regards,
Mark

Answer
Mark,

It does sound like you have an alignment problem.  It sounds like the alignment tech at the second dealer knows what is going on, but I would find one not associated with a car dealership.  And here's how I would sort out whether you've found a good one or not:  

Explain that you have been having tire wear problems and while the rear tires aren't exactly aligned properly, they were close to the factory specs.  But the tires wore quickly anyway.  Is it possible that the factory alignment specs are wrong - especially the tolerance?

If he answers back that the factory specs might indeed be wrong AND says that the tolerances are generally too wide, then you have a winner.

My experience is that published alignment specs are too wide by half.  That's the tolerance, not the target value.  Also, some vehicles come with way too much camber - which promotes handling, but hurts tire wear.  

It's possible your vehicle has both problems.  So be prepared to fix the alignment issue - you will never get to good tire wear without it.  At the very least, get the alignment to within the inner half of the factory spec.

OK, so let me fill in the gaps:

Irregular wear is caused by misalignment and aggravated by insufficient inflation pressure and insufficient rotations practices.  

Needless to say, if you start with new tires and they gradually develop a vibration, alignment is what is driving this - and pretty much nothing else.  (I should mention for completeness that some tires are more sensitive to misalignment than others, but if you get the alignment right, you won't have trouble at all, regardless of the tires.)

In your case, whatever is wrong in the right rear is causing the misalignment and that is causing the irregular tire wear and that results in the vibration (and noise - same thing, different frequency!).

It sounds a bit like you aren't rotating your tires regularly, and that is aggravating the situation.  "They" recommend rotating every 5,000 to 8,000 miles (8,000 to 12,000 km).  Even if the alignment is on spec, my experience is that you will eventually get irregular wear after about 40,000 km.  It just the nature of FWD cars.  It a matter of degree rather than kind.

BTW, the tires aren't going out of balance, they are going "out of round"  (OK, it's a bit more complicated than that, but as a simple description, this phrase works best.)