[packout]

I hit some road hazard and one tire blew out. The dealer recommends changing all four tires. I know the manual recommends that, but my Ascent only has 9,000 miles on it, so the wear on the tires are pretty minimal. At the time, I refused and just replaced the one. After that, I've seen a few posts on the internet about how the tires have to exactly the same to each other, so I am little worried. Should I have replaced all four tires? Thank you so much for your help.

https://blog.tirerack.com/blog/docs-advice-on-tires/needing-to-replace-just-one-tire-on-your-subaru-youll-need-a-shave-as-well

 

[SLCaf]

Shaving seems like a nice solution for a nearly new set. Unfortunately, it says the shaving must be done at the national distribution center, rather than the tire shop. Doesn't sound very convenient.

 

[packout]

Shaving seems like a nice solution for a nearly new set. Unfortunately, it says the shaving must be done at the national distribution center, rather than the tire shop. Doesn't sound very convenient.

I am unclear how the logistics work for this. It could be very impracticable to say the least. Apparently a difference of 2/32nds is the magic threshold.

 

[CaptBackfire]

I blew one of my rear tires a couple months back. Called the dealership and they suggested I come in to have the tire threads measured, and have it ordered already shaved to that wear. A couple days later, I went back to have it fitted back and calibrated. I paid about $160.

 

[e.clinton]

So the other 3 tires are at 7/32, the new one 10/32. The new one is the left rear one, if I might add. Should I replace all 4 or have the new one shaved down to 7/32?

You can get a new tire and shave it down to the desired depth to match the others. TireRack does this. I’m surprised no one else has suggested it.

 

[Robert.Mauro]

You can get a new tire and shave it down to the desired depth to match the others. TireRack does this. I’m surprised no one else has suggested it.

Many people have suggested it above
There's whole conversations about who, and where.

 

[MaxieScruf]

I'll be honest. I found the tires not suitable and changed them out at 3,000 miles. I am happy I did.

 

[absolutsnwbrdr]

New tires vs old tires was just brought up in a Facebook group. Tread depth is not what to measure. Every Subaru forum should have this info stickied (some do): the magical threshold is 1/4" circumference difference. Any more than thst can lead to trouble. Straight from Subaru...

 

[TheLex]

When my Outback blew a rear tire that was pretty new, the Subie dealer just ordered a new shaved tire. I asked them where they got their tires from. Answer: they had a commercial account with Tire Rack. Now you know.

 

[11256]

Look at the treadwear... if there is very low wear... you can get away with just changing one, but if there is a significant difference, change all 4... Hope this helps!

 

[SA2020]

Parking and working on your car alongside a highway may be one of the most dangerous things you'll ever do. My advice is to do your best to get your car running again asap and then get the hell out of there. You can always address the issue once you reach safety.

That's why some states, like Georgia, have roadside service crews that will park behind your car in a giant truck and do the repair. I don't know much about it (is it paid through their taxes, etc) but I see them all the time helping stranded vehicles

 

[FirstSubie]

That's why some states, like Georgia, have roadside service crews that will park behind your car in a giant truck and do the repair. I don't know much about it (is it paid through their taxes, etc) but I see them all the time helping stranded vehicles

Helpful. But also counterpoint: those videos show instances where the videoing vehicle (presumably of reasonable size and ablaze in lights) was parked behind the disabled vehicle, and the person/vehicle still got hit. From these examples, I'm compelled to pull WAY over. Or as mentioned, get off the freeway if feasible.

New tires vs old tires was just brought up in a Facebook group. Tread depth is not what to measure. Every Subaru forum should have this info stickied (some do): the magical threshold is 1/4" circumference difference. Any more than thst can lead to trouble. Straight from Subaru...

Makes me wonder, 1/4" circumferential difference corresponds to what radial difference?

2*Pi*R1 - 2*Pi*R2 = 0.25 inches
2*Pi*(R1-R2) = 0.25 inches
R1-R2 = 0.0398 inches = 0.64 / 16ths inches (less than a sixteenth!)

0.64 sixteenths is a lot smaller than 2 sixteenths!

I'll go with "1/4 inch circumferential for diagnosis of binding, and 2 sixteenths radial/tread for not overly wearing on your differentials."

T.P.

 

[Merope]

^^^ must be new math or something.
0.25" / pi = 0.08" diameter. = 0.04 radius

 

[packout]

My opinion is just that my opinion.....

3/32 sounds like more than minimal wear. I would replace them all at that point. With one taller tire it will not only cause more slippage in the diff side to side but also front to back.

I sure others will chime in too. I am interested in hearing what they say.

I agree, that tread wear is more than minimal and I too suggest changing out all four tires. I have about 24,000 miles on my original tires and they have more tread than yours.

 

[ratbag]

Then buy just one tire and have it shaved and shipped to you.