AWD tire wear dilemma

[mobythevan]

Ok, so I just got my car on the road 3 weeks ago and it is the first DSM or AWD that I have owned. It is a 90 talon tsi. Hear it goes, the alignment was out in the rear and caused the rear tires to wear to about half the tread of the front tires (all this from the previous owner). I got the alignment fixed, but now I have practically new tires on the front and half worn out ones on the rear. Should I rotate the worn out tires to the front or leave them. I don't know how the tires typcally wear on an AWD talon.

 

[weith1111]

Well you normally keep rotating them so they get even wear on each one. What kind of wear did you get, scrubbing of the inner half of the tread gone or what?

 

[95blackGsTurbo]

When rotating on a AWD car though just take the one's from the front to the back and the back to the front. Also make sure your tires aren't directional and have to spin a certain direction.

 

[weith1111]

Are you saying to not rotate in an X pattern? I mean if they are directional tires, of course you can't but otherwise, I thought it was common practict to go corner to corner in AWD vehicles?

 

[95blackGsTurbo]

Nope just back to front like all time 4wd vehicle's.

 

[weith1111]

Hmm...I'm going to ask you to back this up with some facts. Tirerack, Discount Tire, Just Tires, all these places agree with the X or dropping the fronts to back and backs crossing to the front. Wear on the inside of the tire is very different than the outside, switching sides, and front to back makes sure each tire gets even use in every way possible.

Wondering how you leave them on the same side when you have a full size spare that gets tossed into the mix?

 

[95blackGsTurbo]

You can do that but reverse. On RWD and AWD you can move the back straight forward and cross the front's to the back. You always take the drive axle's tire's straight forward or backwards. Then cross the non-drive axle. Since AWD has all axle's driving it is common practice to move tire's from back to front and front to back. You also have to do it more often. About every oil change they should be done theoretically. I just learned from the Moderators of DSMTalk that you should just go front to back, back to front so I trust them.

 

[jtmcinder]

The purpose of rotating tires is to spread the wear around. Since our cars are seriously front-heavy, they wear the fronts faster than the rear (assuming a good alignment). So, if he has worn down the rears, he should leave them there until the fronts catch up.

- Jtoby

 

[weith1111]

The purpose of rotating tires is to spread the wear around. Since our cars are seriously front-heavy, they wear the fronts faster than the rear (assuming a good alignment). So, if he has worn down the rears, he should leave them there until the fronts catch up.

- Jtoby

Shouldn't the circumference be the same on all tires? Wouldn't this be putting stress on the drivetrain as the rears would be (trying to) spinning faster than the fronts?

I'm still curious if it was even wear, or angled from horrible camber or something.

 

[paranoidTSi]

you should have just replaced all 4 tires instead of half and half. Is the trend wear even or is it more on the inside of the tire? If its on the inside your camber may need to be adjusted.

I had a problem with my talon when I first got it, the inside of the tires were wearing out early...got an alignment and new tires..6 months later those were bad. Did the same thing one more time, that set prematurely failed. So I took it to the tire center here and they said the camber needed adjusting.

 

[EvolvingGST]

Shouldn't the circumference be the same on all tires? Wouldn't this be putting stress on the drivetrain as the rears would be (trying to) spinning faster than the fronts?

I'm still curious if it was even wear, or angled from horrible camber or something.

No... factor in braking and cornering... thus front tires wear is higher since front is heavier.

 

[weith1111]

No... factor in braking and cornering... thus front tires wear is higher since front is heavier.

reread. I know that.

The idea was to leave the worn tires in the rear and the fronts would catch up. I was asking if having tires that rotate 900 times per mile in the front and tires that rotate 940 times per mile in the rear would be a bad thing. I think so...

 

[mobythevan]

So, if he has worn down the rears, he should leave them there until the fronts catch up.

That is what I was looking for, thanks

My rear tires are worn across the entire width, not just outside or inside.

I'll leave them on the back for now and when I get new wheels this summer I will put on four new tires.

 

[mobythevan]

I was asking if having tires that rotate 900 times per mile in the front and tires that rotate 940 times per mile in the rear would be a bad thing. I think so...

In reference to this I read a few old threads and the consensus by some was that under-inflated tires would also be similar, causing the diameter difference. The old threads basically said same size tires all the way around, and if some are not iflated correctly or worn more than others the diameter difference between front back is still accpetable.

Now is that opinion??? I did take the car to a reputable shop for the alignment and pointed out the wear difference and they were not concerned even though it is AWD.

 

[Highwayrun]

Swapping wheels from left to right is not that beneficial, since the inside of each tire would still remain on the inside of the car. The tire would need to be flipped on the rim itself, but not all tires allow this.

Swapping wheels from left to right may also not be appropriate with directional tires, due to compromised water evacuation (reversed tread pattern) and reduced dry performance (asymmetric carcass, tread block size, etc.)

The overall tire diameter given by a manufacturer for a free-standing tire is a lot different than when the tire is on the car. From the factory, your DSM's front tires appear much flatter than the rear tires, due to: the extra weight on the front end; the insufficient difference in tire pressure between front and rear; and of course, the difference in camber between front and rear wheels.

Therefore, even when the DSM first rolled off the factory floor, there was more than likely an appreciable difference in angular velocity between front and rear wheels, when the vehicle drove in a straight line.

When you factor in that the vehicle was designed to last a number of years, and run with underinflated tires, turn corners, etc. it becomes obvious that the LSDs are designed to handle a fair bit of slippage in normal use.

As jtmcinder suggested, the front tire wear rate is greater than the rears. My experience has been that the fronts wear much faster than the rears. Therefore, I expect you'll have evenly worn(out) tires in no time at all.

 

[EvolvingGST]

reread. I know that.

The idea was to leave the worn tires in the rear and the fronts would catch up. I was asking if having tires that rotate 900 times per mile in the front and tires that rotate 940 times per mile in the rear would be a bad thing. I think so...

not nec. since you factor in those factors i said earlier you might not make it that different after you factor that in. It is a lot more wear than revolutions. That was my point. So short answer no...

You wont rotate that many more times its a little wear not like the difference between bald tires and new tires. If that is the case where you are that far appart then you should get new tires anyways.

 

[robs90tsi]

Ya, if your rears are worn more than your fronts, then leave the tires where they are until the fronts catch up to the rears.

 

[weith1111]

Swapping wheels from left to right is not that beneficial, since the inside of each tire would still remain on the inside of the car. The tire would need to be flipped on the rim itself, but not all tires allow this.

Haha. I'm an idiot. Good point.

About the revs per mile based on underinflation and different wear...it's understandable there will have to be some slop, as you can't have everything 100% equal, I was trying to point out that with HALF the tread gone, you are consciously throwing it off...a lot.

According to my math, a theoretical 225/50/16 tire would rotate 811.32 times per mile. The same tire worn halfway would rotate 845.68 times per mile. This is practically the same difference between having your fronts be 50 series (845.68 revs) and your rears 45 series (841.7 revs).

I don't think anyone would recommend running different profile tires front and back, so why would it be ok to run half worn and new tires front and back?

I'm sure everything will be ok, just seems contradictory in theory.

 

[r1ashad]

I don't think anyone would recommend running different profile tires front and back, so why would it be ok to run half worn and new tires front and back?

If you had two 47" tires in the front and one 46" and one 45.5" in the rear, then you had a .5" difference in the rear and a 1.25" difference front-to-rear. Maybe the .5" difference in the rear was a main source of the problem in the rear end, but you also have to consider what was going on with the front-to-rear difference coupled with a welded diff. Assuming the front tires maintained grip (due to the extra weight), the rears must have been slipping 3% (or maybe I should say "anti-slipping" since the ground was moving faster than the tires' treads). This rear slip could have been spread across the two rears or it might have been concentrated in the smaller of the two. This would cause the rear diff to be operating at a bit more that 5% (as well as dragging the smaller rear at this rate). And it would not surprise me if the rear's VC couldn't handle that.

Not that I suggest the experiment, but I'd be curious to know what would happen if the you put both 47" wheels in the rear. The front diff is open (if stock), so this might cause less grief.

In any event, it's an interesting post.

- Jtoby

The last quote from jtmcinder can be found on the following thread: http://www.dsmtuner.com/forums/showthread.php?t=165999&highlight=different+size+tire+diameters

 

[weith1111]

Nice! My point exactly. I wouldn't leave them on, but since the OP has most likely been driving like this for weeks, if there was going to be a problem I think it would have presented itself already.

 

[mobythevan]

The car was actually driven like this for over a year by the PO, because the rear kept wearing faster due to the alignment being out. I left them alone so far after fixing the alignment.

 

[1hottalon]

Hey I think you should leave them on the rear until you have enough to replace all 4 tires. replacing 2 on a awd vehicle would give you a vibration if tread patterns are mixed. As for rotation you should rotate Front to Back, Back to Front according to Goodyear and Michelin Tires themselves. Bald tires on the rear you only loose stability not traction.