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Discussion Starter · #1 ·
Hi all,

I've tried to hold off asking this question here but I've read all I can and still confused. I probably need 2 separate threads but...

I've had my Forester Premium (MY2019) for couple of weeks now, circa 40,000kms on the clock. I've had no end of trouble with the TPMS that the dealer can't seem to fix. The light came on and stays on, no reading in the dash for pressures at all. Initially was told by dealer that they thought one wheel sensor was missing but they couldn't confirm - silly I thought. Went to a tyre dealer and they simply checked the valves and pinpointed that the spare wheel was on the car (no sensor) and swapped the tyres round so all 4 wheels had the TPMS sensor in (visual check only). All tyres inflated but still, no dice. TMPS light still on. What to do?

Next issue is apparently the rolling circumference in the front and rear wheels is said to differ by >10mm by dealer, I've been advised that this is harmful to the AWD. There are 3 Bridgestone Duelers (2 with good tread and 1 that is lower) on the car and 1 chinese tyre (looks new), all same 225/55/r18. Bridgestones are 98v while the chinese tyre is 98H. Do I buy 2 new tyres, put them on the front and keep the older, fresher tread on the back (thus relegating the Chinese tyre to the spare) or do I have to buy 4 new tyres? Expensive.

Is tyre wear a factor in rolling circumference or simply tyre brand differences and quality? Does speed rating matter?

Sorry for the ramble and thanks for your help.
 

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2017 Forester XT Touring
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I don't know about in Australia, but here in the US, they can shave new tires to match the older tires. If that's an option, you might consider just replacing two tires. But also consider the tire life lost by doing so compared to replacing all four tires.

You'll probably find a lot of argument regarding the rolling circumference and if it will actually harm the AWD system or not. Good luck with that discussion. :p
 

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2018 2.5i Premium CVT
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Best advice is All four tires identical. Same 'size' tires by different manufacturers or with significantly different tread patterns can have different rolling circumference and exhibit different handling behaviors. This is bad for AWD, and can be bad for handling and safety.

As for tire wear among identical tires, yes it can contribute to the difference over time. Front tires carry a heavier load and can wear down faster. Since I live in snow country, I account for this at the semi-annual summer/snow rotation, by putting the better pair on the front each time.
 

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I agree with @bbottomley about the tire matching / tire wear and to be quite frank, I don't think this is a contentious topic.

There simply is no valid argument (at least one that I have heard) that makes a good case that Subaru (or any of the other AWD manufacturers for that matter), tire producers and other experts in the industry are wrong when they essentially all agree that these factors are key.

btw, the fact that you can't get a reading on any of the pressures seems to indicate a problem with the system, not the sensors IMO. If one, maybe two sensors weren't reading then yeah, I'd probably suspect a faulty / dead battery or something along those lines.

I know there was at least one other thread on this topic and I can't recall if it boiled down to a faulty module on the car or not. ....might be worth digging around.
 

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It sounds like this was a recent purchase (?), and that you inherited a mess from the previous owner.

Tires: You have a Subaru AWD problem and a safety issue here. Not only are the tires not matched in terms of tread depth (rolling circumference) and brand, but also in tire construction, sidewall flex and handling (V vs H).

Best case is 4 new tires. If you just can't, you will need to invest in at least 1 Dueler, and then I'd advise finding a speed shop that can shave the two with deeper tread down a bit. Put the two with more remaining tread on the front.

This is old, but we still keep hearing it referenced:
551928


Concerning your TPMS issues: You need to find a shop that can scan all 4 wheel sensors. A TPMS-style valve stem can be inserted into a rim, but there might not be a TPMS sensor attached to the brass extension inside the wheel. Or the sensor might be resident but damaged. Once they scan all 4 and verify that they are indeed matching, valid sensors, then they need to upload them thru the OBD port to the on-board system. And yes, it's still possible that the RKE module isn't functioning, but get thru the basics first before jumping to that.
 

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AU MY06 XS Luxury Auto
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There are 3 Bridgestone Duelers (2 with good tread and 1 that is lower) on the car
I’d buy two Duelers for the front, then decide between the 3rd Dueler and Chinese for the spare. if 3rd Dueler is ok, I’d lean towards that.

I don't know about in Australia
New Zealand 🇳🇿, not Australia 🇦🇺 😉

I know there was at least one other thread on this topic
Here’s a search, the 2020 ones seems resolved, not sure about the 2021:
 

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Discussion Starter · #7 ·
Thank you very much folks, really appreciate it. I'm leaning towards 2 new Bridgestone Duelers and will put them on the front.

The dealer was really disappointing with the TPMS issue so will go to a tyre place to see if they can scan the individual wheels as suggested. If the in wheel sensors are fine then I'll push for a warranty repair.

Trying not to regret my purchase, the seller has not engaged as well as I would've hoped.
 

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the seller has not engaged as well as I would've hoped.
That’s probably expected considering you’re missing a cargo cover!

I’d get the tyre place to check out the TPMS sensors when you put the new ones in to confirm they’re there, then check with another dealer under warranty. You got at least 3 years warranty in NZ?
 

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Discussion Starter · #10 ·
That’s probably expected considering you’re missing a cargo cover!

I’d get the tyre place to check out the TPMS sensors when you put the new ones in to confirm they’re there, then check with another dealer under warranty. You got at least 3 years warranty in NZ?
Thanks. 3yrs, yes.
 

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2017 Forester Premium 2.5i, 6-speed manual, moon-roof, fog lights, skid-plates, winch, 2nd bedroom
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The new tires should go on the rear axle.
Common sense may say to put them on the front, but the tire experts say put the new tires on the rear.
Google has a lot on this subject, here are 2 links.
Allstate Insurance
Tirerack.com

A friend had a tpms problem with a toyota, the dealer and the tire place blamed each other and neither could fix it. When I got my tpms tool, it was time to play! The sensors looked good and reading the data from the ecu said all was fine. But the light was still on.
So I rewrote the sensor information to the ecu; just to learn the new tool. The only time his tpms light has come back on this past year, was when a tire was low once.

I don't know why that fixed his problem, everything looked the same before and after, except the light now works right.
 
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The new tires should go on the rear axle.
🤔

Deeper tread tires on the rear axle provide better handling, wet grip, and evacuate water, thereby helping to avoid oversteer and loss of vehicle stability on wet surfaces. Deeper tread tires on the front axle can improve wet straight line braking and stopping distance. If only two tires are being replaced, Michelin generally recommends they be installed on the rear axle in the absence of a tire service professional's recommendation or consumer's preference to the contrary.
So handling in the wet vs stopping in a straight line?

If the front wears quicker than the rears, you keep moving the rears to the front and get a pair of new ones for the rear?
 

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RE: TPMS
Even Discount Tire could not get them right on my old Jeep; my Forester had custom wheels on it when purchased from a private seller and I was told the TPMS did not function -- no big deal. It's just a convenience. I would not trust it with my life, anyway.
A tire pressure guage works for this oldschool curmudgeon! (Place a bit of electrical tape over the offending light on the dash if it bothers too much)
 

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RE: TPMS
Even Discount Tire could not get them right on my old Jeep; my Forester had custom wheels on it when purchased from a private seller and I was told the TPMS did not function -- no big deal. It's just a convenience. I would not trust it with my life, anyway.
A tire pressure guage works for this oldschool curmudgeon! (Place a bit of electrical tape over the offending light on the dash if it bothers too much)
I am as curmudgeonly as the next guy, but my TPMS system did properly give me a warning once in the middle of a long trip, which I should have dealt with immediately rather than just pumping more air in. I obliviously drove another 1,000 miles with zero additional TPMS warnings, and I was getting pretty safe feeling when another warning came on only 100 miles from home. This time, pumping in air only lasted 10 more miles. The basic thing happening - which I discovered only too late - was that a very tapered sheet metal screw had just barely pricked the tire, deep in one tread groove, producing a tiny leak. But the 1,000 miles of subsequent driving pounded the screw in deeper and deeper, every revolution making the diameter of the leak larger. I doubt even you would have checked your pressures any more than my car's TPMS system did on this trip, right?
 

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" . . . should have dealt with immediately . . ." Yes! That's what spares are for.

I had a similar incident with a screw in tire. Since then, I have been aware of the need to check the tread carefully should a leak occur and a slight clicking noise with each tire rotation not be evident (it usually is if one listens carefully).

Am glad you figured it out because s&*t happens. Rack it up to experience, my friend.

However, with age, we all tend to depend on these technological and safety improvements more than perhaps we should. In the end, we can only take responsibility ourselves.
 

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Discussion Starter · #20 ·
Hmm ...

For the price of 2 new Bridgestone tyres, I can get 4 new Supercat HT!

Apparently Supercat is made by Bridgestone/Firestone, their budget/entry level brand...

Sooooo tempted.
 
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