[lostcause]

I have an '04 STi. I just bought two Goodyear Eagle F1 D3s (225/45/17) for the rear of my vehicle. I was planning to buy the fronts in a month or two (spreading the cost out). The local Subie dealership told me that a 2/32 difference in tread could cause damage to the differential. I thought it was only it was only if the difference was side to side not front to rear. Also I did not know Subies suffered from this. If the do why the hell is the spare such a terrible mismatch from the OEM tires (I drove almost 100 miles on the spare waiting for the F1s to come in). Any info would be great. I don't want to damage my differential.

[boondocksaint]

Originally Posted by lostcause

I have an '04 STi. I just bought two Goodyear Eagle F1 D3s (225/45/17) for the rear of my vehicle. I was planning to buy the fronts in a month or two (spreading the cost out). The local Subie dealership told me that a 2/32 difference in tread could cause damage to the differential. I thought it was only it was only if the difference was side to side not front to rear. Also I did not know Subies suffered from this. If the do why the hell is the spare such a terrible mismatch from the OEM tires (I drove almost 100 miles on the spare waiting for the F1s to come in). Any info would be great. I don't want to damage my differential.

I think side to side hurts the front or rear diffs, and front to back could hurt the center diff.

Yeah, our cars are crazy with diffs. FWIW, I think you'll probably be okay as long as you aren't driving much and for the same reason you indicate (the spare). The spare is supposed to be the same rotating diameter as the stock tires, though that obviously changes with wear.

My advice? Swap the tires you have around. Put the corded ones on the back and drive the car like grandma until you can put all four new tires on.

[boondocksaint]

ADDENDUM: You might also find a member local to you who's willing to let you tool around on his or her extra set of wheels (winter setup, for instance) if you ask nicely and buy them alcohol/camber bolts/a lap dance/etc.

For this, having your location in your profile would help.

[fullerton]

Frankly, I'd suck it up and get the other two IMMEDIATELY. If you have to eat some credit card interest, so be it.

Interest on a couple hundred dollars < new center diff.

[lostcause]

Originally Posted by boondocksaint

ADDENDUM: You might also find a member local to you who's willing to let you tool around on his or her extra set of wheels (winter setup, for instance) if you ask nicely and buy them alcohol/camber bolts/a lap dance/etc.

For this, having your location in your profile would help.

Unfortunately, I am driving across the country on Friday. No choice - military orders. I guess it makes sense that they can cause damage. The donut definitely was a mismatch. I thought that it felt weird, figured it was tread but I guess it could have been the differential slipping. GUess, I am buying two more tires. Too bad. Really have enough expenses with the move travel costs this month. I just can't find any D3s in the area now. I bought the last two it seems. I never drive like grandma. Just don't have the discipline.

[boondocksaint]

Originally Posted by lostcause

Unfortunately, I am driving across the country on Friday. No choice - military orders. I guess it makes sense that they can cause damage. The donut definitely was a mismatch. I thought that it felt weird, figured it was tread but I guess it could have been the differential slipping. GUess, I am buying two more tires. Too bad. Really have enough expenses with the move travel costs this month. I just can't find any D3s in the area now. I bought the last two it seems. I never drive like grandma. Just don't have the discipline.

I understand. It's best to pony up for the new rubber as the previous posted suggested, then. The interest on a few hundred bucks is going to be $20 over a month or two. Small price to pay for peace of mind, and for the comfort of driving across country in a well-planted STi.

[fullerton]

DO NOT drive long distances on mismatched tires. Be it the spare or new/old tires.

If you have to, get some cheapos at a local tire shop.

[Tortfeasor STi]

Worth noting, the spare is not designed for many miles. Its just there so you can get to a tire store. Its not designed for you to put hundreds of miles on it. Also, its not designed to go above 55 mph. Excessive wear, excessive heat can cause a blow out (so can road debris) and without a second spare you would be SOL.

Also, differentials work by using friction to make the wheels spin at all the same speeds. With tires of different diameters they will spin at different speeds causing excessive wear on the differentials. The front dif. links the two front tires, the rear links the two rear, the center links the front to the rear by the drive shafts. Putting on miss matched tires anywhere has the potential to burn out ALL THREE DIFFERENTIALS as the ABS and other systems try to deal with the poorly matched tires.

Buy all four wheels together and rotate them a couple of times a year to avoid these issues. Buying only two and spreading out the cost has the potential to ruin your car, and cause damages well beyond the price of a set of tires.

So buy those tires before the move.

[T3h_Clap]

Why are we seeing so many of these threads lately?

people really need to read their owners manual!!

do not mis match tire sizes and do not mis match tire brands/models/compounds/load indexes.

max out a credit card to buy the tires if you have to.

$50 overage and 22% interest over 5 months is still significantly less than replacing a center differential.

hell even buy some cheap ass 215/45/17 tires ($60 a pop) to get you across the country.

[lostcause]

I thought the mismatch was on side to side, not front to rear. My mistake. OK, I am buying new ones. Part of the problem I am running into is that tire distributors keep stock based on the number of vehicles registered in the county. Unfortunately, I am at FT. Bragg where there is literally hundreds of high performance cars that are registered out of state. So, local tire dealers do not have sufficient stock for the demand. I spent two days with a list of 6 different tires sets I was interested in. I did not find a dealer with 4 of any of them. I am going to get two more tomorrow, from a different dealer so I will have a set of four.

[T3h_Clap]

here we go.

Different Tire Sizes Front and Rear on a Street Driven Subaru » t3h_Clap’s Wheel33tist Blog

[T3h_Clap]

Originally Posted by lostcause

I thought the mismatch was on side to side, not front to rear. My mistake. OK, I am buying new ones. Part of the problem I am running into is that tire distributors keep stock based on the number of vehicles registered in the county. Unfortunately, I am at FT. Bragg where there is literally hundreds of high performance cars that are registered out of state. So, local tire dealers do not have sufficient stock for the demand. I spent two days with a list of 6 different tires sets I was interested in. I did not find a dealer with 4 of any of them. I am going to get two more tomorrow, from a different dealer so I will have a set of four.

you seem very sincere about the issue, I didn't mean to make it look like i was attacking you.

live and learn.