1 Lucky Texan

Well, I think we may be close to agreeing on something here - not sure. The 4EAT engages more RWD based on wheel speed sensors. And Subaru CLAIMS this could be triggered by as little as 1/4 inch difference in circumference. So, the them at least, it is not trivial. I personally do not know at what point it becomes a PRACTICAL concern. I found this (of course, he might be wrong too); http://64.233.179.104/search?q=cache:4i6AxlLXLt8J:www.forwardlook.net/mml-archive/msg04853.html+circumference+tire+underinflated+distance+speed+rotation&hl=en Oh, and to the other posts, the manual tranny's center diff is viscous LOCKING. Not pure viscous coupled/limited. I guess the fluid heays up and LOCKS to 50/50 until the fluid cools again. I dunno

below is quoted from the second link; >>>>Through its testing, NHTSA found that systems that use sensors to directly measure tire pressure (pressure-sensor based systems) were better able to detect underinflation, had more consistent warning thresholds, and were quicker to provide underinflation warnings than the systems that infer tire pressure from monitoring wheel speeds (wheel-speed based systems).<<<< Could this be BECAUSE the actual amount of rotation IS very nearly the same? And I hope I did not give the impression a FLAT tire would necessarily roll it's full circumference -I bet most of us have seen how the bead can slip or the tire can 'in-fold' on itself and 'skip' when flat. fun stuff to consider

If only I was that articulate! A fun exercise might be to take said vehicle (3 older tires and one new one) to a large parking lot. mark the ground contact point on all 4 tires. Roll/move the car carefully staright forward for - what 20-50 revolutions and stop with one of the worn tires 'mark' on the bottom and see if the new tire's mark is at a different position. Change the tire pressure and repeat. Who knows, we may be able to confirm that it works AND quantify the pressure change required! (I have my doubts.) I still wouldn't know if it was a big practical problem or not. Just don't want a warranty claim denied i guess.

But it's a conformable item. Not a solid disc. Reducing the air pressure just means it is shaped more like a 'track' on a military tank. The actual perimeter in contact with the road is the same - I guess!

here's fe wpics; http://forums.nasioc.com/forums/showthread.php?t=923988 Carl

But if the tire 'just' gets smaller - why wouldn't it wear evenly straight across? I don't even understand what i wrote - lol! Carl

Well, if you knew what all my other cars ended up looking like, you might not be so flattering! hah! I dunno - just trying to keep my head wrapped around this whole tire circumference issue. I WANT to believe it isn't as bad as it sounds. But I also would not want someone to void their warranty or blow up their center diff. It probably is never gonna be a black/white delineation.

My wife's '03 OBW JUST started doing this. It is now so low on refrigerant it no longer cools or defrosts. Perhaps it is a trend or known issue. I plan to put it in the shop in the next week or 2 for that problem and 1-2 other services. I'll try to rport back to this thread.

It was great to meet you and see the wagon! Glad you brought it out.

Could postal vehicles be a special case though? Seems like having 2 wheels over in the gravel/water/leaf encrusted gutter and swinging the car in/out/around the neighborhood at 20mph is gonna relieve a lot more 'bind' than a 30 minute commute at 70mph on a concrete interstate. I dunno

But doesn't this just change the shape of the tire? The ENTIRE 'perimeter' must still travel around (assuming no 'skipping or something). Kinda like a 'half track' in a way. There wouild still be a difference in axle rotation speed I think. I dunno

last bump

Nah, they got responses for that; "can not duplicate problem" "Probably some bad gas" "You DO want us to rotate your tires and change the cabin air filter, right?" lol!

Nah, it was a SC'd 6, looked kinda like this except H6; http://www.mrtrally.com.au/performance/images/St-X/st-x03.jpg

HAH! I also went a a tech school (Elkins Institute - now defunct) "Do you like to work with your hands, but don't like to get dirty? Perhaps, you should pursue a career in electronics!" (I liked to quote that when I was sweating like a hunk of rancid pork, standing in the direct Texas sun in August, putting magnetic marks on 30,000 feet of armored logging cable for hours on a Saturday!) good times

I've looked for it once or twice after the fact, but I swear I saw a photo of Subaru showing a supercharged H6 at a car show from a coupla years ago. It had a VERY custom looking intake manifold!

Wonder if it can run pump gas or need av fuel or something? crazy

Yeah, better come with a 12 pack of new trannies - your gonna need 'em!

Yeah but what kinda MILEAGE does it get? (I HATE that question - lol!)

It may be difficult to find 16" wheels that will clear the rotors. They may exist - just something to be aware of.

I suppose, if you bought the car used, someone COULD have put an 'underdrive' pulley on it. But, yeah, many cars I've had will do that at least a little.

I would be interested to know if its OK to upgrade the fronts only or if all 4 corners should be upgraded simultaneously.

In addition to the experienced help you may receive here, you can visit http://www.tirerack.com and investigate 'plus 1' sizing your wheels.

I don't think replacing a clutch at 70K means a car is unreliable. For that matter, at 70K, a car could need a lot of TLC, especially if it was neglected by the former owner. You might also consider having the rear main seal changed during the clutch overhaul.

I forgot if this is a turbo or not. maybe the turbo oil seals are bad? I dunno