Celica Forums General Discussion Exterior Big wheels = problems?

My room mate had a nice Eclipse w/18's on it before he got rid of it. He said after he put the 18's on it, he had lots of transmission problems. Is this common or does he not really know what he's talking about? I cant see why bigger wheels would affect a transmission..any input is appreciated.

I guess it could be a bigger strain on the tranny but i have never heard this as a common problem. The biggest issues i hear is of course the added weight and rotational mass slowing you down. Also, mostly on SUV's and such the brakes may need to be upgraded to slow the larger heavier rims.

Nope, your friend is absolutely correct. Think of it like this, your wheels are basically gears that are connected to your engine through the axles. When you increase your tire size you do several things.
*raise the cars center of mass
*more kenetic energy gained from bumps
*your tires push BACK on your engine for as much as your engine pushes your tires

It works like this... by increasing your tire size you force your engine to essentially work at a higher gear ratio to move your tires. By updating your gear box like on most heavily modded cars this isn't a problem because more "race designed" gears can compinsate, stock gears however can't always do that. Bigger tires produce more torque when they skid or slip, which causes damage to the tranny. Also because of the larger wheel there is greater angular inertia within the engine. Because larger wheels are often times heavier they have larger rotational kenetic energy, so the engine does the same amount of work as it would for the smaller tires, but much of the work is "wasted" resulting in wear on your engine. Because the center of mass is higher the angular force from any bumps or other things in the road also take more of a toll on your engine than they may if your car was lower. Which is why lowering a car with bigger tires is important, not only for looks.

Hope this answers your question.

That makes perfect sense. Well stated!

well shit...more reason to get my car lowered sooner

yea, that gives me an excuse to lower my car, just like my car being keyed gave me an excuse to put on a alarm/keyless entry system.

I am not surprised Mitsubishi are known for Really weak tranny's.