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Discussion Starter · #1 ·
Ok given set gear ratios, tire diameter can affect ratios too..

imagine tiny diameter tires on our car. Redlining 1st would yeild about ~20-25 MPH..
the opposite is true too, much bigger diameter would mean longer gearing meaning higher speed for a given RPM..

Now this is only true of the diameter of the tire on the FRONT right...?
well what about on AWD cars? what happens if you have different diameters on the front and rear and a perfect 50/50 torque split? how are the ratios affected?
 

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Discussion Starter · #4 ·
oh shitt, but hell im sure there are little differnces anyways because of tire wear and what not...
BUT theoretically, how would it affect the ratios?
 

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It would most likely make that overall gear reduction on one axle different then the other. So if you ran smaller front tires and larger rear tires the front would have shorter gearing then the rear. It's not going to be friendly though on the drivetrain. Cars equiped with LSD's should also not run on a small donut spare for an extended period of time either.
 

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Ok given set gear ratios, tire diameter can affect ratios too..

imagine tiny diameter tires on our car. Redlining 1st would yeild about ~20-25 MPH..
the opposite is true too, much bigger diameter would mean longer gearing meaning higher speed for a given RPM..

Now this is only true of the diameter of the tire on the FRONT right...?
well what about on AWD cars? what happens if you have different diameters on the front and rear and a perfect 50/50 torque split? how are the ratios affected?
I see what you arer asking so ignoring all the other replies in this thread which according to my knowledge are pretty correct.

The diameter of the wheel will only make a difference if that wheel is directly connected to the motor, aka the driveline. So in an AWD car if you had 30's up font and 12's in the back, your diff would explode:D
 

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Discussion Starter · #8 ·
HAHA omg guys i know the diff would give out but theoretically if it was ok to drive like that.. how would the gearing be affected? ie redling 2nd would normally yeild 60MPH with stockies.. what about w/ changed tires size...

im guessing an average of the tire diameter would be the gearing factor.

and plus if the center diff would explode, why doesnt the little differences that come with front and rear tire wear affect the diff?
 

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Why do you keep asking the same stupid question and ignoring the answer? In regular wear and tear the differences aren't enough to make any difference at all. Putting different size tires are a big difference that would result in fucking shit up badly.

Theoretically if you were to put smaller tires on the front of a awd car and it somehow didn't blow the diff then anytime you moved you would be peeling out with the front tires while the rear ran normally.

Think of it like a car with a posi track rear end. Any time you turn the car you hear the tire "squealing" (the inside tire). This is because one tire is turning faster than the other (ie on a right hand turn the pasenger tire {inside tire} is actually moving accross less ground than the driver side tire {outside tire}.

The outside tire moves at the actual speed, however since the inside tire is directly conected to the outside tire it is forced to turn at the same speed even though it's not moving the same distance therefore it is spinning out/squealing.
 
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You wouldn't actually be affecting the ratios per say, But you'd be screwing with the variable speed sensor which is programmed for a certain tire size. Bigger tires wont really give you longer gearing, just longer and slower acceleration, but I understand what your saying.
 
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