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Old 04-18-2007, 12:34 AM   #1
slayers_x
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Member#: 101220
Join Date: Nov 2005
Chapter/Region: SCIC
Location: Long Beach, CA
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MY05 imprezaRS
riding on open diff

Default 2 Different Sets of Tires

I been reading around the forum that having two different sets is bad and can mess up your center differential for the STi and the WRX follows somehow. 1/4" rolling circumference...

WRX = front open diff and rear vLSD
STI = front LSD center diff and rear LSD
GC RS = front open diff and rear vLSD
GD RS = front and rear open diff

i'm just wondering how does it affect me since i have the GD RS with both front and rear open diffs. it is okay to run? or will i somehow out of nowhere destroy my diffs?
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Old 04-18-2007, 02:35 AM   #2
rougeben83
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Default

The important think is the 1/4" rolling circumference. If you absolutely have to use 2 types of tires, measure the circumference of all 4 and make sure the lowest number is within 1/4" of the highest number.

Also, try to keep the same type of tires all around - it wouldn't be smart to run snows in the front and azenis in the back, for example.
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Old 04-18-2007, 07:49 AM   #3
UkNuck
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Quote:
Originally Posted by slayers_x View Post
i'm just wondering how does it affect me since i have the GD RS with both front and rear open diffs. it is okay to run? or will i somehow out of nowhere destroy my diffs?
It's the CENTER diff you will hose
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Old 04-18-2007, 08:56 PM   #4
slayers_x
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Join Date: Nov 2005
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riding on open diff

Default

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Originally Posted by UkNuck View Post
It's the CENTER diff you will hose
where's the center diff for an RS?
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Old 04-19-2007, 06:38 AM   #5
waktasz
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Rtfm. . The front and rear diffs don't matter in this case. What matters is your center diff will be trying to equalize the speeds of the front and rear tires all the time causing it to work harder.
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Old 04-19-2007, 08:48 AM   #6
Howl
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In simplistic terms, as the power comes out of the transmission is goes into the center diff, which splits the power between the front and rear driveshafts. The power going along the front driveshaft is split again at the front diff sending power down each of the front axles, and the power going along the rear driveshaft is split again at the rear diff sending power down each of the rear axles. If you use tires of different sizes the axles will be trying to move at different speeds. Axles can move at different speed for short periods of time, but if they are forced to spin at different speeds for a long period of time heat builds up in the diff and it fries.

If you put one smaller tire on one side of the car and one larger one on the other the axles on either side will be spinning at different speeds and your front or rear diff will fry. If you put two smaller tires on the back and two larger tires on the front (or vis versa) the front drive shaft and the rear drive shaft will be moving at different speed and that will fry your center diff.
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Old 04-19-2007, 10:48 PM   #7
MPEJ20
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Default im having the same problem

i got a flat tire a month ago and had to replace it with different manufacturer tire, same size but different tread and speed rating....i ve been driving on it for 2000miles so far...how close am i to damaging my center diff??? getting scared and ordering pirelli pzero nero today....help!!!
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