After reading through all the postings, the following precipitates (+ some of my own advice I would like to pass on):

• Wear / damage to the suspension / steering components will show up as tire-wear if not dealt with....
• Tire-wear is an expensive diagnostic method (to diagnose suspension / steering system wear/damage.
• Un-even tire-wear (i.e. inside or outside only wear) is never a tire-problem (but always a symptom of steering / suspension misalignment)
• Unusually short life-time on tires (even wear) is usually a driver problem (too hard on the brakes, too hard on the accellerator)
• It is usual to wear the shoulders on the front tires round. That is why it's agood idea to "rotate" the tires (every 10 k miles...) - i. e. move the rear tires to the front and the front tires to the rear - taking care to let the tires roll the same direction all throgh their lifetime (even if the pattern is omnidirectional). This is true for evry car, but even more improtant for front wheel drive vehicles (the XC90 is front wheel drive, even AWD models).

Also, toe-in wheel allignment should be "demystified". It is perfectly possible for the dedicated do-it-yourself mechanic to assess the toe-in by using a rod (of some sort, preferably a bent one) and a mark on the middle of the tires. First measure the distance between the marks - when the marks point forwards. Then roll the car until the tire-marks point rearwards and compare the measurements. This should give a measurement within +/- 1 mm if you take care....and will usually put your mind at ease that your wheels are not misalligned....
You will however need to make sure that there is no slack in ball-joints or wheel bearings - which of course will invalidate any wheel allignment measurements....