Rotating tires...

takza · Post by **takza** » Tue May 11, 2004 11:47 am

Needed: four identical tires at the same PSI and rotated regularly?

With the 4WD system on the Tercel, where there is no center differential, the front axle and the rear axle are solidly locked together when in 4WD. This is an advantage off road, since 2 of 4 tires have to slip to stop the car...in theory at least.

On a dry road, the only way the 4WD system can "adjust" itself betwen the front & rear axles in a turn is for at least one tire to slip on dry pavement. This is not a good thing to have happen since there is a lot of stress put on the drive train before the tire slips.

Since this car is usually driven in 2WD, the front tires tend to wear faster. If you don't rotate them, you might find it more difficult to get into and out of 4WD at times. Not to mention that a set of tires might last longer if rotated.

The rotating pattern:

1st rotation - diagonally - right front to left rear exchanged....left front to right rear exchanged.

2nd rotation: - front to back - right front to right rear exchanged...left front to left rear exchanged.

3rd rotation: same as 1st rotation.

This pattern lets each tire spend some time on each corner of the car...to even out wear.

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First rotation with a new set of tires:

After 5K miles, my formerly new Kumhos show the fronts worn down to a little more than 7/32" and the rears worn to 9.5/32". Original tread depth was supposed to be 10/32".

Can still go straight on a dry road in 4WD for several miles before it becomes difficult to get out of 4WD.

Front tires were worn the same amount right and left...rears were worn down only .5/32" and were equal in wear.

The front tires were run for the 1st 4K miles with the toe-in off by quite a bit....causing greater wear.

Avg tire wear in 5K miles is around 1.75/32". Since the wear bars take up 2/32" (wear limit) and the tire started with 10/32"...there is really only 8/32" of tread to work with.

So at almost 2/32" per 5K miles I might be lucky to get 25-30K from these tires.

But they will be FUN & STICKY MILES.

* After 11K miles...all four tires now have about 7/32" tread left...and since the wear across the treads looks to be even...I'm not going to rotate them for another 5K or so...to let the front tires wear down some.

* After 18K miles...tires have an avg tread depth of 6 to 6 1/2 / 32". Got 4 to 4 1/2 / 32"
to go....maybe another 18K?

3A-C Power · Post by **3A-C Power** » Tue May 11, 2004 12:25 pm

You mentioned changing tires from one side of the car to the other. I've heard that this is bad for the tires since it reverses the direction of torque being applied to the cords and causes cord separation from the rubber. I'm studying tire mechanics which should provide some answers. I would like to rotate my tires in such a way that each tire gets equal use at each location. That the tires would have equal wear patterns regardless of differences in wheel alignment. You can also include the spare in the rotation so that it is worn the same as the rest and the overall life of your tires will be increased by 25%.

GTSSportCoupe · Post by **GTSSportCoupe** » Tue May 11, 2004 2:08 pm

Nice writeup!

I only ever change my tires from back to front and not from side to side. Mainly because I've owned directional tires and I don't want to have to re-mount them on the rims everytime I rotate the tires. My main concern is that the front and rear pairs are as evenly worn as possible.

takza · Post by **takza** » Tue May 11, 2004 5:51 pm

With my previous budget tires. I'm pretty sure that the right side front tire tended to wear a little faster. But they spun fairly easy. With the Kumhos it isn't so.

I've heard the thing about it not being a good idea to reverse rotation with radial tires...but on several occasions that I've mentioned this to people at tire places, they said it wasn't true.

I've experienced problems with this when reversing OLDER radials...I think they get "set in their ways" or something...more like they are deteriorating as far as an even tread depth and when you reverse them the dynamics are much different and they bounce. Maybe if you rotate them front to back and side to side...this forces them to wear more evenly? :huh: