Is that really lightweight? Seems pretty fridgin heavy to me!

WIll this really slow down the 350 as compared to the OEM 20 lb 17s? It is wider, thus more contact patch right? (275/40s)

 

That's extremely heavy. You sure you have the weights right?

 

Yeah, I dunno which SSR rims you're looking at. The Competition rims aren't even close to being that heavy. Check out www.wheelweights.net for some research.

 

The SSR Competition wheels in 18x10.5" size are 19.2 pounds. The SSR GT3 in 18x10" size are 25.5 pounds.

 

yes, im refering to the GT3s, my bad---guess those wheels are out of the question---quite pricey too

 

Just an FYI, I think you are off on the stock 17's weight as well. They come in at more like 24-25 pounds rather than 20lbs.

 

ahhh...that helps, thanks.

 

Get the new GT2. Weight is very similar to the Type C.

 

I'm new to this part of the forum so don't flame me if this has been covered before. Anyhow, was wondering about the larger rim size bennies. Being an engineer I understand the weight issue for accelerating, braking and handling. However, it seems counter to go larger in wheel radius for 3 reasons: 1) increased weight for the same wheel design, 2) increased rotating inertia which will generally go up by the square of the wheel diameter and 3) larger unsprung mass working against suspension and handling. I can see a slight decrease in rolling resistance and possibly better aesthetics. Are there other reasons I'm not aware of?

 

No, I think you pretty much covered it--Just forgot strenght , i.e. upgrading to a 3-piece wheel/2-piece wheel and clearence for bigger brakes (but in reality people who Auto X will really need these things)

--Mechanical Engineer I suppose right? Planning on majoring in that next year. What do you do now? Any advice? (sorry to be off the subject here)

 

VQ35DES, any form of engineering is a great vocation. I've done civil, mechanical, aerospace, materials, and electromechanical for both work and hobby. You'll find the college curriculum for engineering a bit more work than some others but well worth it later in life.

One of it's side benefits is the background to rationally question and understand some of the hoopla behind product trends like many of those in the auto aftermarket. It also gives one the capability to actually add engineered products and/or improvements to their cars. I've noticed several engineers on these forums that have developed products for their wheels and then offered them to others as a side business. I have a few on the drawing board myself.

enjoy.

 

Don't forget that switching to a larger rim while maintaining the same OD will result in a smaller sidewall---which increases lateral tire stiffness and reduces slip angles. Everything in engineering is a compromise. BSME PSU 99'.

 

Agree with the sidewall stiffness benefit for cornering. But one can do the same with smaller diameter wheels and pick up the bennies of reduced weight for braking into a corner and accelerating out of the corner? I'm sure folks have done trade studies for various driving situations and optimized the relevant parameters. The racing teams are fanatical about these issues. I'll take a look at what various auto racing setups have evolved to.

The reason I'm curious about this issue is the apparent dichotomy between the power boosting which I presume is for improving acceleration and some of the other "upgrades" with features that appear to detract from improved acceleration.

Anyhow, I'm here to learn.

 

Yes, you can. The end result is the same as if you had swapped your differential to a higher numerical ratio. Keep in mind that this solution for the track will cause your speedometer and odometer to register high by a percentage equal to the percent decrease in tire circumference.