I was looking at 18 inch wheels for my third gen. I have been told that a larger wheel can have too much spinning mass, when then affects braking, handling and overall performance. Does anyone know anyhing about this?

Nick

 

Yeah, spinning mass, commonly refered to inertia in the engineering world is basically the resistance to something being moved. If something has a high inertia, then it takes alot to get it moving, and consequently takes alot to get it to stop.

The farther the weight is to the outside of a circle, the more inertia it has. You can have 2 circles that weigh the same and have the same OD (outside diameter), but if one is a hoop, and the other is a solid circle, then the hoop will have more inertia, because all of it's weight is concentrated to the outside. (remember, both weight the same)

If you want to think about it on a more linear scale. If you have 2 rods that are the same weight, and one is solid and has a small diameter and is solid, and the other one is larger and hollow, the larger one will be stronger to resisting a bending moment.

Ok, enough of the lesson. Basically metal (rim) weighs more than rubber and air (tire). So the larger rim/tire combo will have more inertia. Therefore reducing your RWHP a small amount. Hope I didn't lose you in my little lesson.

 

I see said the blind man.

So when does it come to the point where I am sacrificing performance for cosmetics? 17 inch, 18 inch, 19 inch wheels.....

Nick

 

like the saying says: Bigger is better.....

 

Yeah, I wish I knew how much performance you would sacrifice. It's the same principle as an LS1 drive shaft. Aluminum is lighter so less inertia. I'm sure you would see a difference if you wen't from 16's to 19's.

 

I have 17's now. I was thinking about going with 18's in the back, 17's in the front. I am considering THESE

Nick