MishaA wrote:
> Nate Nagel Wrote:
>
>>Secondly, if you get new tires, you should rotate the tires so that the
>>newest ones are on the rear of the car, to keep the vehicle stable in
>>bad weather conditions.
>>
>
>
> Could you please elaborate on this? Till now I was sure in the
> opposite.
> Thanks, Misha
>
>

Most people think that the reason that you always used to put the good
tires on the back of a car was because they were the drive wheels. They
were traditionally the drive wheels, yes, but the *real* good reason to
do that has to do with keeping the back end from coming around on you,
especially on hard braking, or to a lesser extent, cornering. The whole
deal is that a rubber-pavement interface (like the contact patches of
your tires) has a significantly higher coefficient of static friction
than sliding friction, therefore if a wheel loses traction and locks
under braking, you want it to be the front, so that the vehicle stays
straight (the greater force from the still-rolling rear tires will keep
the vehicle stable. In the opposite situation, the car is essentially
trying to balance itself on its front tires, and any perturbation will
make the rear end try to come around to one side or the other.) Also,
if either end loses traction while cornering, for any but the most
skilled drivers, it's safer for it to be the front (understeer) rather
than the rear (oversteer.) The correct procedure for recovering from
understeer would be to quickly but smoothly lift off the gas, or even
brake slightly, to allow weight to transfer back to the front to give
the front tires more bite, which is the instinctive reaction of most
people. To recover from *oversteer,* the correct procedure would be to
actually accelerate gently to transfer more weight to the back, while
countersteering. Most people can handle the countersteering part, but
the accelerating thing is counterintuitive. So there's two situations
where for most drivers keeping the good tires on the back is of definite
benefit.

That said, on a FWD car you still want to have *good* tires on the
front, or you won't be going much of anywhere in the snow. Also,
obviously, for maximum safety you'd really want to have decent tires all
around (I don't know what your current "good" pair is like, so I can't
actually offer real advice specific to you) but in the case where a
driver is forced by circumstances to replace only two tires, generally
the new tires should *always* go on the back.

good luck,

nate

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