i'm having an argument with a friend of mine about evo's and most awd cars in general. it involves running different sized rims/tires on an evo and the effect it would have on the t-case. I'M NOT LOOKING TO DO THIS, OR PROMOTING IT, JUST USING IT AS AN EXTREME EXAMPLE TO DETERMINE WHETHER OR NOT IW OULD MAKE A DIFFERENCE. THIS IS IN RESPONCE TO A DEALER TELLING A CUSTOMER OF MINE THAT, ALL 4 CORNERS MUST HAVE THE SAME SIZE AND BRAND OF TIRES OR THE T-CASE WILL BLOW. I KNOW THE BRAND THING IS BS, BUT THE SIZE SHOULDNT MATTER EITHER???

I say that on an evo, if you wanted to, you could run different sized rims in the back and the front and that the overall diameter does not matter if its different because the cars are designed to have a limited amount of slip. I believe that doing that is the same as if you were driving your car around on a sharp turn for 12 hours straight, because the inside wheels would never rotate as fast as the outside wheels, so the fact that the wheels do not rotate exactly the same doesnt mean anything. its not the same as a truc thats 2wd and put into 4wd where you drive it on the street and the inside wheels are chirping because they are trying to keep up with the outside wheels.

My friend believe that the rotations must be the same and that if you drove around in a tight circle for hours on end, the t-case would eventually blow. But if this were true then all evo t-cases would blow eventually because of turning???

IF ANYONE KNOWS THE REAL ANSWER PLEASE POST UP. AGAIN I'M NOT LOOKING TO DO THIS, SO PLEASE DONT POST UP "WHY WOULD YOU WANNA BLAH BLAH BLAH BLAH"

THANKS IN ADVANCE

 

i've found that as long as you keep them with on 5-7% of each other you will be fine.

I use to run a staggred setup on an awd tsi a long time ago and never had any problems AutoXing or drag racing, and that was with inferior technology compared to the Evo Transfer cases

 

The only issues I could see happening is burning through differentials faster....they are designed to allow each wheel to go at a different speed, which they do just fine....it just means the differentials would be spinning different. Certain differential types, this won't make a difference, but in others, it will. A clutch type, for instance, and maybe a viscous coupling.

 

over time you WILL destory the center diff... diff size left to right youll wear out the front and rear diffs.. its the same as running a one big and one small tire on a rear lsd on a rwd v8, you will destory the clutch pack.. its like constantly slipping your clutch.. rachet, clutch pack, hyd., or welded rear, the results will be the same.. the only thing you could is run diff. widths front to back... roadrace evos have done it... i cant tell you anything else..

 

Theoretrically, I think your firend is right, but I think it would take a very long time to destroy the tcase in that manner. Offroad trucks chirp the tires on turns because they have either spools (welded both axles together), or they have detroit lockers (ratcheting locker) and are on the gas in the turn. The spooled trucks will chirp all the time, no matter how they are driven. I had one on my baja truck and it was annoying.

But anyway, I think the limited slip theoretically would wear out if the tires were rotating at different speeds, because the clutches would be constantly slipping.

 

If you drove your Evo in a tight circle hours on end, then, yes, your center diff, tcase and rear diff would be taking a lot of abuse. This is one of the reasons why any Evo owner should be very proactive as far as changing their transmission/differential fluids goes (mine didn't last the recommended service interval, for example). The same goes for different sized (diameter) tires. You could run different tire widths, but if you have ACD, then it's pretty much pointless, since the ECU will usuall "correct" any handling anomalies that it detects.

l8r)

 

had a tire customer where a new employee put the wrong size tires on his cherokee (225 front vs 235 rear) in front in the winter, wound up costing about 3k to get fixed, shop payed for the TC.

 

Read your Manual......

 

As far as different tire brands go, it's worth checking the manufacturer's info on rolling diamater as well. While in most cases similiarly sized tires should be pretty close, I've seen some noteworthy differences when researching different tires.