There is no need to dynamically balance the wheel unless the tires are
removed and reinstalled on different wheels for some reason. Dynamic
balancing is not done "on the car", but rather, on a dynamic balancing
Actually, dynamic balancing can be done either on the car (using a
machine made for that purpose) or with just the wheel/tire combo on a
balancing machine. "Dynamic" merely means that the tire is spun on the
machine and balance is measured in 2 axes, as opposed to the old static
balance using a bubble level.
Really, "on the car" balancing should never show much improvement over
off-the-car balancing unless the hub is out of balance or the wheel
doesn't index properly onto the hub- both mechanical defects that SHOULD
Yes, it is a possibility to do "on the car" balancing, but that is not
(necessarily) what is meant by dynamic balancing. Dynamic balancing
only refers to the idea that the wheel is rotated (either on or off the
car) during the balancing.
I'm of the mind that "on the car" balancing is only a band-aid approach
to some other problem with the wheel, hub or axle. You should be able
to balance a wheel&tire and then mount it on any axle and be good to go.
Makes sense to me. I think this falls under the old adage of; "If it
ain't broke, don't fix it."
The more time you let someone (including one's self) change things, the
more opportunities there are for problems and mistakes.
I'm glad you see that. I've given this explanation before and lots of people
thought it was ludicrous. Your point is bang on. Tire rotation may possibly
increase the tread life of tires (especially if you throw the spare into the
rotation). But even if it makes sense for this reason alone, a dealer gets
absolutely no benefit from your extra tire life, but potentially has all the
grief to deal with if you end up with shimmy and shake as a result. I've
even hear that service reps will tell a customer, in low tones with a wink
"You know, I just can't give you a reasonable deal on a rotation because
(insert some stupid justification here), but (and please don't say you heard
it from me), Bobby down the street will do it lickety split for next to
The idea is to have all tires wear approximately evenly, so that they
all wear out at the same time. Then you can replace them with a matched
set of new tires, rather than have two new tires and two partly worn old
tires (or having to waste some of the tread life of the old not worn out
Timothy J. Lee
It all depends on what you're trying to maximize.
If you're trying to extract the utomost performance from every tire,
then don't rotate because once a wear pattern is established, switching
it to a different corner of the car would result in a sub-optimal
On the other hand, if you don't expect to push your car to its absolute
lateral G limit all the time (as in the case of 99.9% of daily driven
cars!) then rotating the tires and tolerating a slightly sub-optimum
contact patch right after rotation WILL get longer service life out of
The vast majority of cars on the road- ESPECIALLY front-drive vehicles-
benefit a lot from tire rotation in the long run.
I don't uderstand the theory of this statement. If you are running a
tire which has worn a particular way, and now has a sub-optimal contact,
wouldn't you think that the "high spots" (the areas with greater
pressure in the new location) would wear faster and therfore negate the
total tire life assertion?
Yes, but the tire thus lasts longer than it would if you left it where
it was so that it wore through to the cord in the first high-wear area.
Frankly, most cars don't wear tires that badly except some FWD vehicles.
Its entirely possible to wear two sets of front tires on an FWD down
to the wear indicators without showing significant overall wear on a
single set of rear tires. But by that time the rear tires are so aged
that they don't have the grip they should and are subject to tread
separation and other problems. It seems to me, based on several
experiences now, that modern tire designs are more sensitive to the
aging of the rubber compounds than the tires of the 70s. Even if you had
a set of tires stored in a dark, dry garage for 6 years, the odds of
them lasting a full lifetime when you put them on the car will be VERY
small- they'll probably develop cracks or separations long before they
I agree, rotation will lengthen the life of the individual tire, but the
tires will still wear at the same rate as a set.
Here's an example: Because of the large amount of rear camber, my Z3
wears the rear tires (on the inboard edges) twice as fast as the fronts
(which wear pretty evenly) . I can either replace the rears only at
~20k miles and get a total of 40k miles out of 6 tires, or I can rotate
the fronts to the back and thereby get a bit less than 30k miles out of
the original set of 4, and then have to buy 4 new tires.
Plus you either have to swap the wheels yourself or pay someone to do it.
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