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Tire Replacement...all four Mandatory?


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60 replies to this topic

#51 Smpol19

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Posted 08 June 2006 - 01:45 PM

If that were true firstwagon, then the limitations imposed by all our user's handbooks about the doughnut spare wheel use would be absurd. Why then only 50 miles per hour and for a limited distance?


While i agree that it's important to replace all 4 tires on these cars, and probably a good idea on any car. Every car I've ever driven has similar warnings about the use of the spare tire, so i'm not sure that that has anything to do with the sensitive AWD compotents.

#52 phatline

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Posted 08 June 2006 - 11:15 PM

I will test this theory tonight by adjusting my tire pressures until the axels are of equal height, then checking the rotations/circumferences using the "parking lot" method suggested on these forums, and post back here.


Hi everyone,

Ok I used frag's parking lot method today. 42 revolutions of the front tires resulted in 41.66 revolutions of the rear tires. Assuming an 80" tire circumference, that means the rear tires are about .65" larger in circumference. Significantly past the .25" specification given by Subaru. I'm going to check into the economics of shaving down the rear tires since there's good life left on the fronts.

I'm curious what measurements others have made of their tires?

I also checked the axel heights: 31.2 cm front, 31.6 cm rear. Letting out 1.5 PSI only brought the rear axel down 0.1 cm, so I concluded there was no reason to repeat the circumference test or try to achieve another .3 cm drop.

#53 otis

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Posted 08 June 2006 - 11:42 PM

I'm curious what measurements others have made of their tires?

I bought a used tire when one of my tires blew. I chose a "similar" type of tire with a comparable tread depth. when I did the 40 revolution circumference test, the new tire was about 0.75" bigger than the smallest tire. 2 tires were pretty close (within 0.10"), the other was about 0.33" off. that was almost 2 years (and 20k miles) ago. I should re-check them to see if it's changed at all.

#54 phatline

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Posted 09 June 2006 - 01:17 AM

I bought a used tire when one of my tires blew. I chose a "similar" type of tire with a comparable tread depth. when I did the 40 revolution circumference test, the new tire was about 0.75" bigger than the smallest tire. 2 tires were pretty close (within 0.10"), the other was about 0.33" off. that was almost 2 years (and 20k miles) ago. I should re-check them to see if it's changed at all.


Otis, thanks for the data point. My fronts and rears agreed with themselves (right and left) almost perfectly (no detectable shift). I just bought this car used but it looks like it's been running on the two different sets of tires for 20k. Due to warnings from folks here (and the .25" Subaru tolerance spec) I'm seriously considering having the larger tires shaved down, or even replacing all four tires.

#55 jib

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Posted 14 June 2006 - 05:52 PM

You may have difficulty in finding someone who will shave a tire which has been run. A pebble in the tread could damage his equipment.

jack

#56 phatline

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Posted 14 June 2006 - 07:01 PM

You may have difficulty in finding someone who will shave a tire which has been run. A pebble in the tread could damage his equipment.


FYI, I took it in yesterday and he said it'd take longer b/c he has to clean all the pebbles out of the tire. Guess I was lucky to find someone who would even consider it.

It would cost $75 to dismount, shave, balance, and re-mount two tires. We decided the tread was low enough that it's best to just buy new tires and be done with it. The rears have a higher treadwear rating thant he fronts, so even if I got them matched up now the fronts would wear down and create a mismatch in the future.

Which begs the question, any tire recommendations? Is it even worth putting an "SUV" (light truck) tire on the Forester, or is an all-weather passenger tire adequate? I want something quiet and efficient on the highway but capable of decent mud/snow/gravel driving a few times a year. I'm a little cautious about passenger tires w/ sloping sidewalls--dont' want to get a flat 20 miles down a fire road. At least there is a full size spare in the Forester...

#57 1 Lucky Texan

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Posted 14 June 2006 - 07:08 PM

FYI, I took it in yesterday and he said it'd take longer b/c he has to clean all the pebbles out of the tire. Guess I was lucky to find someone who would even consider it.

It would cost $75 to dismount, shave, balance, and re-mount two tires. We decided the tread was low enough that it's best to just buy new tires and be done with it. The rears have a higher treadwear rating thant he fronts, so even if I got them matched up now the fronts would wear down and create a mismatch in the future.

Which begs the question, any tire recommendations? Is it even worth putting an "SUV" (light truck) tire on the Forester, or is an all-weather passenger tire adequate? I want something quiet and efficient on the highway but capable of decent mud/snow/gravel driving a few times a year. I'm a little cautious about passenger tires w/ sloping sidewalls--dont' want to get a flat 20 miles down a fire road. At least there is a full size spare in the Forester...


In addition to suggestions here, you might enjoy looking around at www.tirerack.com . I have done busines with them and was pleased - but that was rims with tires mounted. I have 'heard' that local tire chains will sometimes match prices with tirerack.

good luck

Carl

#58 Sinister Subaru

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Posted 15 June 2006 - 05:21 AM

So here's the deal...a guy I work with has a Forester (2004 5spd X). He wanted to spread out the cost of tire replacement so he went to the tire dealership and wanted to replace only the front tires because in his rotation, the fronts had the least amount of tread.

His plan was to work into a routine where he was only replacing two tires at a time instead of a full set of four (same brand and model of tire).

The tire store tech gave him some **** and bull story (I think it's bull) about how it's an all wheel drive car - you HAVE to replace all four tires at the same time because if you unbalance the system with difference in tread depth and traction you can destroy your AWD drivetrain!?

Make sense or is this worthy of a BS flag?


Nope, no BS. You really do have to replace all 4 tires at the same time or the AWD will be "unbalanced." By allowing this to happen you would wear out the AWD quite quickly.

#59 Hank Roberts

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Posted 27 June 2006 - 08:16 PM

..... any tire recommendations? Is it even worth putting an "SUV" (light truck) tire on the Forester, or is an all-weather passenger tire adequate? I want something quiet and efficient on the highway but capable of decent mud/snow/gravel driving a few times a year. I'm a little cautious about passenger tires w/ sloping sidewalls--dont' want to get a flat 20 miles down a fire road. At least there is a full size spare in the Forester...


I'm echoing that question -- I will probably buy a 2003 Forester X next week -- haven't seen it yet, from old family friends, and 6 freeway hours from home.

16" steel wheels.

I may well buy six tires.

Why six? Here's why I wonder about light truck tires:

The way I usually kill tires is by breaking the steel belts on sharp rocks -- I use a nasty forest road 'graveled' with sharp hunks of rock, that was used by logging trucks for one contract then abandoned to public use. If not broken steel belts then sliced up sidewalls are common. The local (50 miles away) tire stores all know that road.

I always carry two full sized spares, on every car I've used for 20 years on those roads.

I'll have to buy an extra wheel for the '03 Forester.

Given all these cautions -- anyone recommend a particular tire? Light truck even possible?

#60 outback_97

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Posted 28 June 2006 - 08:18 AM

My two cents on more aggressive tires:

I have Firestone Destination A/T's on my car, and like them. They're not a LT designation tire but they seem more solidly built for "off-road" use and less prone to sidewall damage than my old Michelin regular all season tires. I have driven them in snow, gravel(with sharp rocks), dirt and sand and they do very well. No opportunity yet for mud, it's pretty dry here most of the time (except snow in the winter). The vast majority of my car's miles though are unfortunately driving me back and forth to work. These tires do that well also.

Here's some drawbacks: I went with 205/75/15 tires, one step up from stock. Now I cannot fit a tire of that size in the spare well. I have probably lost some hwy mileage, around town seems not to be affected. There is more road noise than a typical quiet all season tire, I don't find it objectionable though. And the higher sidewall flexes a bit more in hard turning. There was *very* slight rubbing on compression and sharp turning but that went away when I installed Scorpion springs to lift the car slightly.

For those with 16" wheels, you'll unfortunately have a much harder time finding tires that fit, or at least you'll have fewer options. There's not much room for larger without rubbing.

Steve

#61 Hank Roberts

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Posted 30 June 2006 - 10:26 PM

OK, I bought the 2003 Forester; one tire has several sidewall cuts, one of the white rubber -- not down to the sidewall cords and not bulging but risky once anything else happened to poke at that spot. I drove it 250 miles of Highway 5 in 100 degree weather uneventfully.

Off to the local tire store after the 4th. If they can find me one matching used (Yokohama, likely the tires that came on the Subaru 20k miles ago? -- the spare has never been used at all) I'll delay and hope for suggestions.

The '03 Forester glovebox manual says use a 4=tire "rotation" -- tires always kept on same side, just back to front each time.

That means any spare's always going to be the wrong size.

We always carry two full size spares and break one (both tread and steel belts) a few times a decade, before we wear the tires out -- sharp rocks on our nasty road.

Never had AWD before -- with AWD I'd like a six-tire rotation, starting with six new tires -- that's theory, but this may be the time, on this car, to start that way.

Consumer Reports has recent tire recommendations for car tires.

I'd prefer 'Light Truck' for better sidewalls if I can get them in 16" -- most likely not? Next idea is go to 17" wheels --

QUESTION: Did Subaru ever made 17" wheels in steel == the Forester XS comes with 17" aluminum, but I gather aluminum wheels crack in rough use.

EDIT: found this link in the "rear disk brake swap" thread:
http://wac.addr.com/...obs/wheels.html
big list of wheels and sources

I guess they'd fit any Forester. Wonder if Subaru has a shim or adjustment for the speedometer, like the old 1960s Dodge trucks, for changing tire sizes?




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