Dangerous 2004 Forester tires?

I've been reading this group for about 4 years and don't recall any incidents. Just out of curiosity, was it driver or passenger side? The fast lane, driver's side is right next to the median and it collects all manner of sharp trash. I'd bet that she hit a piece of sheet metal or body trim and that caused the blowout. The debris would not have to be big enough for her to notice.

No. The blowout was on the passenger side away from the median. And she never strayed from her lane. So my question remains. I wonder what could have caused the complete shredding of her new tire.

I had a flat tire that couldn't be repaired at about 15K miles on my '99 Forester. I checked around and found there is an allowable tolerance for the diameter - they don't have to be EXACTLY the same. I replaced the one tire and had no problems. I've replaced all four since then.

The same thing happened to me on a brand new rental Town Car about ten years ago. After installing a good replacement tire, I noticed that it got very hot to the touch after driving for a while. IMO, the knuckle had been installed at an angle, thus basically dragging the tire across the asphalt.

Something tells me that's less likely to happen in a Subaru (or go unnoticed for that long) but check your tire temperature after a stretch of highway driving.

Florian

"s" wrote in news:9oJoc.123300$G snipped-for-privacy@nwrddc02.gnilink.net:

Thats correct. All 4 tires need to be nearly identical in circumference. According to the owner's manual and Subaru's site:

"On All-Wheel Drive (AWD) vehicles, it is extremely important that the rolling or outer circumferences of the tires be within 1/4 inch of each other."

"Exceeding this 1/4-inch difference in tire circumference can place unnecessary wear on drivetrain components, possibly causing them to wear out prematurely."

Source:

There is a tolerance, but as FuzzyLogic points out, it is only a 1/4" in circumference, which is not a lot of tolerance. I would be willing to bet you surpassed that tolerance and went against the specs if you had 15,000 miles on them. As you said, maybe you have had and will have no problems, but it is a gamble you should recognize that you took. I did the same myself, but I knew there was some risk involved. Seems to have paid off okay, since 2 Foresters have 79K and 92K on them now. I know I had the issue with one, and possibly with both, I can't remember. One had a difference of almost 3/8" between tires when I measured. The fact is, you can end up with that much difference just from uneven wear due to poor alignment, a problem that plaqued the early Foresters till Subaru changed the specs for alignments. Since then, tire wear has been much improved, at least for us.

Has anybody figuerd out what that equates to using a thread tool?

Thanks -H.

In addition to the issue with tire circumference, there are issues with towing that are different than other cars. I suggest Subarus are not for you - shop among another brand.

Carl

1 Lucky texan

s wrote:

Math says the 1/4" difference in circumferance is about 4/100" of radius, which is just a bit over 1/32" difference in tread depth. I wonder what the manufacturing tolerances are? That seems an awfully small amount.

I took a chance on replacing only one tire at 13k miles and have had no problems now at 36k. There has been some view here that the specifications were written by Subaru's lawyers, not by its engineers. Advice I got here was to put the new tire and the spare (remounted on an alloy wheel) on one side, and put the demounted, good, original tire onto the steel wheel as spare.

My original tires are due for replacement in the not too distant future, so the situation will become academic I hope.

84-318i wrote:

On a standard 205/55/16", the circumference is 78.16" which equals 810.68 revolutions per mile. A 4/100" difference (increase) in radius would amount to 2.6 revolutions per mile. If you're going sixty, that's 2.6rpm at the wheels, the differential and the center diff.

I don't believe a viscous coupling would engage at this rate and I guess the AWD clutch mechanism in an automatic would certainly slip more than that - even if fully engaged. It is in the interest of the manufacturer to err on the safe side, especially since it's you who's paying for a whole set of new tires instead of just one.

Florian (please do correct my math if I am off here...)

A single sharp object puncturing the tire at highway speeds could cause shredding within seconds. I had that happen when I passed by some construction debris - the tire was gone in 10 seconds, but the steel rims survived. I've also had a minor flat on "runflat" style tires. I could still drive at 50 MPH with no tire pressure, although it was a bit noisy.

A spontaneous blowout could come come from an improperly mounted or underinflated tire. However - I'd guess a sharp object probably created a puncture that would have been unrepairable. A nail or screw puncture can be patched, but a 1"+ cut can't be, and might keep on expanding at highway speeds.

Yes. It isn't so much for "4 wheel drive cars", but specific to various cars. Most AWD cars are likely to have some restrictions, but if cars with torsen differentials (like many Audis) have any restriction, it will likely be more relaxed than for cars with viscous-coupled LS diffs (like many Foresters. Mine has 2. Some have none).

For Subes there are specs for how close the tires must match. I forget what the specs are for my Forester, but IIRC they're more relaxed than the specs for older AWD Subes.

Well, it is TOO common for me.

Same thing happened to me, also at almost exactly 5,000 miles. I simply installed the spare, came home, and got a tire dealer who was glad to order that tire for me. I now have over 14,000 miles on the new tire/3 old tires, and no more problems. There was what appeared to be a "cut" in the tire so no dealer guarantee was in effect. (Darn, those Yokohama tires are not cheap!)

Never had a blowout but the Yokohama tires that came with out 1998 Forrester were the worst tires I have ever had in 40 years of driving. They wore out in only 18K miles and were terrible in the snow here in NH. We got over 45K on each of two sets of the Bridgestone replacements as well as reasonable traction.

We are looking at a new Forester and will probably change the tires out the day we get it as they all appear to have the Croak-ohama tires. Too bad they put crap tires on an otherwise excellent vehicle.

Geee my 2000 forest came with yokos H?Ts and they were excellent all season tires except for wear as I only got ~28,000 to the wear bars. I do keep regular pressure checks and most blow-outs I'm aware of were caused by low pressure or hitting something. My present Yokos (avid touring) now have ~

Weather has a lot to do with it. We have had a hot streak here in the high

90's and there is tire debris all over the interstate here. Low air pressure will cause more friction raising tire temps. Too high of temp will blowout. I suspect hot pavement doesn't help either.

No problems with the Yoko Geolanders on my XT that has done 35000 km on Australian roads and tracks. My only concern is that they seem to wear fairly quickly.