My dealer rotates the tires on our '12 XC70 at each service - front to rear. This car is still under warranty.

It is not the diameter of the tire that is important, it is the circumference.

If you do a search, it is possible to find the values of tolerances for circumference differences for various makes of cars.

Volvo's tolerance is smaller than Subaru, but all AWD cars have this problem.

I always rotated the tires on our RWD cars and did not do that on our 850s. I always mark the wheel positions with crayon whenever I took wheels off.

Before I put a set of tires (for instance snows or summer tires) I like to put all 4 tires together in a box shape in their respective positions to look at their wear and any shape differences.

I had a '72 Volkswagen 412 and it would squirm if I rotated its Michelins - that ended my tire rotations on cars with independent rear suspensions.

When I first read this post, I asked what is recommended in the manual??
Next on the thread was Klaus with the answer..... Thanks.

The manual guidance sounds rather hokey?? When the AWD systems became available they stressed the importance of correct inflation and tread wear (keep all tire
diameters as close as possible or the AWD sensors will think a wheel is slipping and adjust, etc).
**Tires are rotated front to back and back to front, same side always.

** I have used this rotation on our AWD and V70 Volvo's with great
success.

One thing I am not sure of is if the newer AWD cars have been programed
to deal beter with miss-match in tire diameters.
Art

For others following this thread, I have included the Owner's manual write up. I guess one should then buy just 2 tires at a time because the front tires will wear faster than the rear tires. That will make it hard to match the tread pattern, regardless of manufacturer, which raises another issue.

I will continue to rotate the tires at every oil change and have even wear on all 4 and then buy 4 replacements.

Owner's manual:

Tire rotation
Your vehicle has no recommended tire rotation. The following information is intended to help you understand why.

Tread set
As a tire ages and the rubber cures, front and rear tires set at different angles. Therefore, if tires are rotated, the tread will eventually set at an angle that is a compromise. Even if ride, handling, and road noise may still seem acceptable, they may not be optimal. Further, tires that are rotated, but not on a regular basis, may actually cause more tire noise, faster tire wear, and unpleasant changes in steering feel and vehicle handling.

A tire that can fully adapt to its position will provide better steering feel, lower tire noise, and better fuel economy.

Braking stability performance
Your vehicle is driven mainly by the front tires, which will wear faster. This can be beneficial. Having more tread on the rear tires will help reduce oversteer. Oversteer is when a vehicle wants to keep turning because of momentum and dynamic forces on its suspension.

Suspension wear diagnostics
Every suspension needs periodic inspection and maintenance. A tire's wear pattern can be an aid in detecting a suspension problem. Each tire, if left in place, tells a story about the suspension. Tire rotation, on the other hand, could make suspension wear harder to detect. Early detection is very important, because suspension problems can make tire wear worse.

If you do rotate your tires...
Please follow the tire manufacturer's recommendations, as outlined in the tire manufacturers tire warranty pamphlet.
--
Keeping it running is better than buying new