Tire rotation

[ChevyMan]

To whom it may concern


My daughter wants to purchase two new tires in front for her BMW all-wheel-drive auto and I suggested to install the new ones in the rear wheel as sort of rotating the tires. Does AWD autos need not rotate as cars with either front OR rear drives ? What is your opinion (or advice) ?

[Ken]

To whom it may concern


My daughter wants to purchase two new tires in front for her BMW all-wheel-drive auto and I suggested to install the new ones in the rear wheel as sort of rotating the tires. Does AWD autos need not rotate as cars with either front OR rear drives ? What is your opinion (or advice) ?

Hi, Larry, this is the best short answer I can find you.

In vehicles equipped with all-wheel drive (AWD) systems, the transfer case (gears that transfer power from the transmission to both the front and rear axles) and the car’s internal computer work together to send power out to each wheel. The amount of power-per-wheel can vary, depending on each wheel’s individual work load. For example, in a straight line each wheel carries a reasonably similar load. In a cornering situation the stress on each wheel is very different.
So the amount of power the internal computer sends to each wheel – based on what your AWD vehicle needs to go down the road – helps to manage how hard the transmission and transfer case are working.
With inconsistent outside diameters caused by different tire sizes, tread patterns or tread depths an AWD computer’s readings will fluctuate. Various wheels will receive inefficient or incorrect power loads. As a result the drivetrain (computer, transmission and transfer case) must constantly readjust, doing more work than necessary and eventually, may break down. While replacing your tires in sets of fours will greatly reduce your risk of problems, regularly rotating your tires and keeping them properly inflated will ensure your new tires wear evenly. Even tread wear is key to keeping your all-wheel drive system operating at its best!

Having gone through quite a few web-sites to try and answer your question, Larry, my best solution is to change all four tires so that all tires are matched for make, tread pattern and rolling radius.
I understand that Tire Rack have a facility for 'shaving' tread off new tires in order to match them to part worn tires. This, to me seems to defeat the purpose of new tires.

My answer - Advise your daughter to change all four tires and rotate them regularly.

Ken.

[ChevyMan]

Thanks much, Ken, you have similar opinion as I do regarding rotating all tires regularly for even wear throughout the life of each individual tire. And I understand that one should replace ALL tires after continuous service of five or six years regardless of thread wear. True ??

[Ken]

Thanks much, Ken, you have similar opinion as I do regarding rotating all tires regularly for even wear throughout the life of each individual tire. And I understand that one should replace ALL tires after continuous service of five or six years regardless of thread wear. True ??

I fully agree, Larry. For me five years would be a good target - if I could get a set of tires to last that long.

Ken.