Tire rotation policies. What's to be afraid of?

Bimmers don't rotate their tires in America either (neither do beemers, but they can't).

Bimmers don't rotate their tires in America either (neither do beemers, but they can't). "

Ever heard of a front-wheel drive BMW??

Frighteningly enough rumor has it that BMW is planning a FWD chassis now. I hope this isn't the end of the RWD sport sedan... what's next, a v-6 that's "almost as smooth" as an inline 6?

Sadly, the new Cooper Mini is that way.

--scott

what's fwd got to do with it? averaging the wear among 4 tires by rotation doesn't mean the wear rate is any different, just that it's not concentrated. and on a fwd drive vehicle, it's especially important that the rear tires are in the best condition to prevent unpowered rear end flip-arounds - a condition from which you can recover in rwd, but very hard to do on fwd.

Jim Beam: "what's fwd got to do with it?"

Everything! BMWs have amonge the best f-r weight ratio of anything on four wheels. 52-48, 51-49, compared to front-wheel only: 60-40 at best, 65-35 typical. Those need rotation, where as rear/all-wheel drives generally do n't. If they do, it's typically side-to-side, assuming non-directionationa l tires.

wheels. 52-48, 51-49, compared to front-wheel only: 60-40 at best, 65-35 typical. Those need rotation, where as rear/all-wheel drives generally don't. If they do, it's typically side-to-side, assuming non-directionational tires.

ok, i'll ask again, what does fwd have to do with it? where does this bizarre presumption that tire wear rates have to be even come from? brake pad wear rates aren't. disk wear rates aren't. so why tires???

Ok you know what? Someone else can explain to Jim Beam about the effects of different weights on tire wear. I'm through with this guy!

different weights on tire wear. I'm through with this guy!

dude, we all know it happens - i'm simply asking you why you think it's important to have all your tires wearing out at the same time?! it's not a trick question.

Primarily so that you have equal traction at each corner to make handling more predictable. It also allows you to get more miles out of a given tire by balancing the wear across the tread.

ok, but you don't have that.

1. you don't have even weight distribution most of the time.

1. you don't have even forces even if you had even weight. braking is obvious, but less well understood is that because rear wheels follow front wheels, they cut inside the arc of turn. by definition, a smaller turning radius at the same angular velocity means they're subject to more lateral force. that increases wear on rears, and you'd be able to see it if other things like front wheel braking wear didn't overwhelm its visibility.

that is a common misunderstanding. the wear rates are the same. tires wear because each time a patch of rubber contacts the ground, it leaves a small layer of rubber where it was. then you have additional rubber loss when there's any sliding - when a contact patch "squidges" on the ground, the edges slide. then you have additional loss through cornering, braking, acceleration, etc.

so, the only effective way you can reduce wear is to reduce the squidge. even if you filled the tire with incompressible water, each individual rubber block is still subject to this local distortion and thus still wears. [but you still want it - it's what provides traction!]

bottom line, what is commonly believed to be "increasing the mileage" is actually just averaging - iow, yes you may increase the mileage for an individual tire, but the one that's now in its place after a rotation is now wearing at exactly the same rate as the previous one. and actually at a greater rate initially since it now needs to get its rotation "sense" pattern worn in [greater local sliding].

Steve W:

Thanks for taking a turn at talking to a wall. :)

s of different weights on tire wear.  I'm through with this guy!

well, one reason I could think of is that for a front wheel driver front wheels do all the work. Anyhow, 90% of it. Acceleration, braking, steering, you name it. And the first two of the set have everything to do with wear. So you have them close to wear bars and all of a sudden you get hydroplaning with the lesser ones which all of a sudden means no steering. You don't want that in the litigious us of a. Solution from the car industry? Rotate the tires.

I'd personally go through 2 sets of directional tires in front before swapping the worn out rears and won't worry about rotation if I were in sunbelt, but I live in snowbelt and don't mark the wheels. So seasons change f*ck knows which wheel ends up in f*ck knows which corner. Would you consider that rotation?