I have a 2003 Outback H6. The tires on the car right now are bridgestone Potenza E92QZ (97h). The two front tires are worn down along the outside edge so I need to replace those two. However I can't find that model of tire anywhere, not even any info on it anywheres on the web in regards to diameter or circumference. The bridgestone Potenza 92E model looks like the tread is the same (From looking at pictures online). Wondering if anyone would have any suggestions on if I should replace the two front tires with 92E's or would I risk doing damage. I believe the E92QZ were stock tires the cars came with new, but that's a guess.

I'd just replace all 4. No sense in trying to get those exact tires and shave them down...

I'd just replace all 4. No sense in trying to get those exact tires and shave them down...

 

 

Same thought.........Subies with all wheel drive need to have all four tires with the same tread depth to operate properly. Running tires with different tread depths cause Subies to develop expensive drive train problems.

if your trying to find the same tread pattern and everything i would give a call or log onto http://www.tirerack.com ...

if your trying to find the same tread pattern and everything i would give a call or log onto www.tirerack.com ...

 

Tirerack.com shows the OE tires as Potenza RE92's (97H). The sidewall pic and tread pic on tirerack.com look exactly the same as my E92QZ (97H). So i'm guessing they must be the same tire. I would be buying two used tires RE92's with the same tread depth as the two E92QZ tires I would be leaving on the back of the car. I just wish I had a way to confirm this 100% as I don't want to do damage to the car.

Tirerack.com shows the OE tires as Potenza RE92's (97H). The sidewall pic and tread pic on tirerack.com look exactly the same as my E92QZ (97H). So i'm guessing they must be the same tire. I would be buying two used tires RE92's with the same tread depth as the two E92QZ tires I would be leaving on the back of the car. I just wish I had a way to confirm this 100% as I don't want to do damage to the car.

 

The only way to be 100% sure is to mount the tire and measure the circumference between the two.

Finally found a tire shop that knew what they were talking about, the two models are 100 percent the exact same other then the writing on the side, the ones ending in qz are whitewalls, the others are blackwall writing. But I will measure circumference when I get them mounted just to be sure.

If the rears have wear, and you replace the fronts, the circumference won't match.

 

Did the edges on the front wear from a bad alignment?

Low pressure?

 

Can you just rotate the tires- it could be edge wear just from normal turn scuffing, the front edges always wear a bit more than the rear edges.

 

 

Dave

Front Tires both have wear on inside and outside edges, dunno if it's from previous owner not rotating tires or the car needs an alignment. My plan was to replace front tires with some used tires (Exact model tire I currently have) with the same amount of tread remaining on back (about 80%) I would make sure I measured the circumference to make sure they match. I believe as long as circumference is within 1/2" they are fine to run?

 

If the rears have wear, and you replace the fronts, the circumference won't match.

 

Did the edges on the front wear from a bad alignment?

Low pressure?

 

Can you just rotate the tires- it could be edge wear just from normal turn scuffing, the front edges always wear a bit more than the rear edges.

 

 

Dave

I believe as long as circumference is within 1/2" they are fine to run?

Spec is 1/4 inch.

I think the best post-install check would be to find a flat empty parking lot, park the car at one end, chalk the tires where they hit the ground (one thin line straight down), drive 10 tire revolutions, and see if the chalk marks all point down.

 

Find the mark that has moved the largest amount (car would need to roll backwards for it to point down), roll the car back so it points straight down, then find the mark that needs the car to roll forwards the most for it to align, mark the car position, roll the car forwards so that furthest-off mark tire is pointing straight down, measure the distance the car has moved, if its more than 2.5 inches you're boned.

 

Something you can do is take one 'new' tire and put it on the front, and put the other 'new' tire on the back, on the opposite side of the car. This will 'average out' the front-rear circumference difference, but if you have a limited-slip rear differential, it'll hose that.

 

If you have an AT you could put in the fuse and put the large tires on the front and run 'em down a bit.

 

 

Dave

I measure circumference with a simple dressmaker's tape, looking for all four tires to be within a quarter inch. Seems easier than the parking lot "10 revolution test", except you have to remove the wheels from the car.

I measure circumference with a simple dressmaker's tape, looking for all four tires to be within a quarter inch. Seems easier than the parking lot "10 revolution test", except you have to remove the wheels from the car.

 

I just meant, if you really wanted to get nuts with it!

 

Also, if you were concerned about the actual rolling circumference, you would have to do it that way.

 

For tires of the same model, however their rolling circumference varied from the tape-measured circumference, it'd be the same (no impact).

 

For tires of different model#s, or from different manufacturers, the difference might be important, that is the tape measure might show them to be OK, but the rolling circumference might not.

 

 

Dave