Tire shaving for Subaru tire replacement

[y_p_w]

So I found a screw in my tire, and finding a place that was willing to patch it (at least until I could replace it) was an ordeal.

Now I have a 2004 Subaru Impreza WRX with one patched tire that has decent tread everywhere except the inside shoulder. I rode on it flat for days without realizing it, and I think the negative camber had something to do with that shoulder wearing quickly. I'm keeping an eye on it and will probably replace it in a few weeks.

I actually have decent tread left on the remainder of the tires. It's 6/32"-7/32" on the remaining Bridgestone RE960AS tires, which came from the factory with 11/32" tread depth. I've gotten 26K miles on this set, so I'm hoping that I can push 40K at least before getting new tires. I don't particularly want to get a new set now, and the shop I went to said that their distributor could shave the tires (maybe to 7/32") which should be acceptable for a Subaru.

Anyone tried this on an AWD car? I'm thinking that the shaving process probably won't trim it exactly like regular wear would achieve, but it would be close enough to reduce torque binding on the diffs. I needed to stop riding on the compact spare (on the rear). I was getting this whooshing sound coming from the back about a half second after I took off, and I wasn't sure if it was the center diff or the rear LSD. I tried keeping the speed down by taking surface streets to work, but the noise was really annoying.

 

[HTSS_TR]

If you must use compact spare on cars with rear LSD, then the spare must be on the front. If you have compact spare on the rear, it will destroy the LSD in very short time.

In the mean times waiting for the replacement, you need to move the compact spare to the front.

 

[Bill in Utah]

Don't go by tread depth.

When we had a major accident @ 8k on our new Outback I had them get a new tire since the original tire/rim was destroyed.

The new tire was the same brand, size and model so we thought it would be fine. According to the tread, less than 2/32 difference between the old ones and replacement.

Once we got it on the road within 3 miles the AWD light went on and things went down hill from there.

We pulled the fuse and drove it another 10 miles home. I measured the overall circumference of all tires and the new one was almost 2 inches larger. Really messed with the AWD system.

I could not find ANYONE who would shave a tire for on road use.

If they shaved it there would not be anything left for use. Plus even if it would have worked, they are afraid of the lawyers for on road use.

So we ended up putting 4 new Triple Treads on the car.

Take care and good luck.

 

[bepperb]

For me, a tire starts at 10/32 and ends at 4/32, so if it were my tires they would already be 2/3 of the way shot.

So, I'd rather buy two new tires and replace an axle set than to buy one brand new tire and have them basically cut the life in half (and pay them for it) before I ever even use it.

I deal with snow, but I assume you have enough rain that tread depth is a similar concern for you.

 

[Bill in Utah]

Except you have to replace ALL the tires on a Subaru.

Can NOT go with just 2. The system WILL notice.

 

[y_p_w]

Originally Posted By: Bill in Utah
Except you have to replace ALL the tires on a Subaru.

Can NOT go with just 2. The system WILL notice.


Mine's a 5-speed, so there is no warning light. I was always under the impression that the manual transmission models were more robust than the automatics. They don't provide a FWD override (I don't think they can since it's purely mechanical) and still use the compact spare. I'm not sure about the LSD. I don't race and rarely use it in snow. I've also heard that most viscous coupled LSDs are effectively open diff after 60K miles, although I've never really abused it.

I think I'll just roll the dice and get one new shaved tire. I don't think the shop/warehouse is worried about liability since they've done it before. It's always random buying new tires anyways regarding size. I remember buying a set once, and the shop said they could only get two from their regular warehouse and were going to another warehouse (with less profit) for the other two. If there's a chance at a mismatched set from different production dates, then that could happen anywhere. That could include the same warehouse sending the same model tires from different production runs.

 

[Button]

+2 for changing all 4 tires. One of my wife's employees ruined his differentials on his STi because he did not change all four.

@ the end of the day, it cheaper to replace tires than differentials.

Good luck,
~Button

 

[97f150]

Originally Posted By: Button
+2 for changing all 4 tires. One of my wife's employees ruined his differentials on his STi because he did not change all four.

@ the end of the day, it cheaper to replace tires than differentials.

Good luck,
~Button


Agreed, I would leave nothing to chance, especially with tires that are almost half worn. Also, be darned if I pay someone to shave a brand new tire to almost half life. Maybe if they charged me only half price.

 

[Jim 5]

Originally Posted By: Bill in Utah
Except you have to replace ALL the tires on a Subaru.

Can NOT go with just 2. The system WILL notice.



Sounds like a good reason to buy an extra factory matching rim and full sized spare to keep in constant rotation with the other 4. This way if a road hazard takes out a tire, you've can put the spare into use (and buy a cheap/used spare to keep in the trunk). Chances are, you can still use up the rest of the undamaged 3 tires plus your 5th matching tire before you encounter another road hazard and have to buy a full set.

 

[friendly_jacek]

This is the part I did not like about Subaru. Very sensitivity to tire size differences. Yet, compact spare tire. Go figure! I had to replace 4 tires once for this very reason.

 

[Button]

It's not just "Subaru's" . . . it's any vehicle w/ AWD!

 

[bepperb]

"It's not just "Subaru's" . . . it's any vehicle w/ AWD!"

Now that I would disagree with. For example, a CRV or Rav4 doesn't have a locking differential anywhere, they use a computer and the ABS system, and further either turns the AWD off at a certain speed.

So besides pushing a button under the dash to calibrate the ABS system to the new larger diameter tire, there's no mechanical reason you couldn't have tires mismatched on those cars.

Of course, neither has AWD performance anywhere near a Subaru (though I'd probably take one in the snow over a Legacy with 50 series summer tires, which I see here all the time).

 

[Pop_Rivit]

You'll be a lot happier replacing all 4 tires.

We have an 05 OB Sport (Impreza based) and replaced the pathetic OEM Bridgestone tires at around 32K. Big difference in the handling, and the Michelin Harmony tires we purchased still have plenty of tread left after 45,000 miles of wear.

 

[Bill in Utah]

Originally Posted By: Jim 5
Originally Posted By: Bill in Utah
Except you have to replace ALL the tires on a Subaru.

Can NOT go with just 2. The system WILL notice.



Sounds like a good reason to buy an extra factory matching rim and full sized spare to keep in constant rotation with the other 4. This way if a road hazard takes out a tire, you've can put the spare into use (and buy a cheap/used spare to keep in the trunk). Chances are, you can still use up the rest of the undamaged 3 tires plus your 5th matching tire before you encounter another road hazard and have to buy a full set.


I love this!

The only problem is I buy directional tires so 3 would wear at one rate and the other 2 at another.

Guess I could flip the tire and rebalance every xx thousand miles?

But a EXCELLENT idea and something I WILL do next time.

Can not put the normal tire in the spare tire well as on the Outback the tires are large. But it can sit in the garage

.

 

[y_p_w]

Originally Posted By: Pop_Rivit
You'll be a lot happier replacing all 4 tires.

We have an 05 OB Sport (Impreza based) and replaced the pathetic OEM Bridgestone tires at around 32K. Big difference in the handling, and the Michelin Harmony tires we purchased still have plenty of tread left after 45,000 miles of wear.

I ditched the OEM Bridgestone Potenza RE92 tires at about 8K miles although they looked like they could go 40K miles with enough rotation.

What I've got right now are the considerably better handling/steering/water shedding Potenza RE960AS. I'm happy with the tires right now which have 26K miles on them and look like they could go at least 40K as a set.

 

[jeff8407]

You really have to do your homework with Subies. The different models (WRX, STI, WRX TR) from different years have different front and rear differentials and some will work with a slightly offsize tire and some will not. Here is a simple answer a Subie tuner told me, "it it requires LSD fluid make certain the tires match--shaving to the same circumference is fine, if it doesn't take LSD fluid tires don't matter."

 

[Bill in Utah]

My 2007 Outback does NOT require LSD fluid and within 10 miles of driving with 3 OEM tires with 8k and one new tire (same size, brand and model but slightly larger) with 10 miles on it I had the AWD light come on and the car started having major drive line issues.

Changing the tires to all the 4 same size fixed the problem immediately.

So that answer does not work with the Outbacks/Forester models.

Take care, bill

 

[KLowD9x]

Originally Posted By: bepperb
"It's not just "Subaru's" . . . it's any vehicle w/ AWD!"

Now that I would disagree with. For example, a CRV or Rav4 doesn't have a locking differential anywhere, they use a computer and the ABS system, and further either turns the AWD off at a certain speed.

So besides pushing a button under the dash to calibrate the ABS system to the new larger diameter tire, there's no mechanical reason you couldn't have tires mismatched on those cars.

Of course, neither has AWD performance anywhere near a Subaru (though I'd probably take one in the snow over a Legacy with 50 series summer tires, which I see here all the time).


What about when you need AWD to function? Are you saying that it won't with mismatched tires?

What if it does come on? Would you not get some nice driveline twist and possibly shear something? The Volvos I work on have a predetermined failure point between the center differential and the transaxle. If the computer controlled AWD kicks in with wrong tires, there is a good chance you will shear the teeth off of this sleeve once you get a large amount of driveline twist up.

 

[bdcardinal]

Originally Posted By: KLowD9x
What about when you need AWD to function? Are you saying that it won't with mismatched tires?

What if it does come on? Would you not get some nice driveline twist and possibly shear something? The Volvos I work on have a predetermined failure point between the center differential and the transaxle. If the computer controlled AWD kicks in with wrong tires, there is a good chance you will shear the teeth off of this sleeve once you get a large amount of driveline twist up.


[censored] angle gears. im getting a new one tomorrow.

 

[KLowD9x]

Originally Posted By: bdcardinal
Originally Posted By: KLowD9x
What about when you need AWD to function? Are you saying that it won't with mismatched tires?

What if it does come on? Would you not get some nice driveline twist and possibly shear something? The Volvos I work on have a predetermined failure point between the center differential and the transaxle. If the computer controlled AWD kicks in with wrong tires, there is a good chance you will shear the teeth off of this sleeve once you get a large amount of driveline twist up.


[censored] angle gears. im getting a new one tomorrow.


Are you sure it isn't the splined sleeve between the angle gear and transaxle?

I have never replaced an angle gear due to failure, but I have had hundreds out due to that sleeve.