I disagree when people say that 15" have less rotational mass than 16". Cuz once you put the tires on, they would be pretty much the same if the in favor of the 16". Ive never acually weighed a tire but it just seems like alloy would be lighter than an extra inch on the sidewall of rubber. I just think that the rubber would be heavier. Yes, i know i am probably wrong, but i just decided to let my mind flow.

 

hmmmm, you think eh?
well let have experience and facts decide the issue... not your imagination or deep thoughts.

really this has been beaten too death!!!!!!!!!!!!!
AAAAAAAAAAAHHHHHHHHHHH!!!!!!

sorry if that seems rude, I am just a facts based guy, and I know my car is faster on 15" wheels, handles better (in my opinion of what is better) on 15" wheels, and is less expensive to purchase initially and also to maintain a 15" wheel setup.

 

I knew that i was gonna get proven wrong, but i was just thinkin about the topic because ive heard it so much on this board. Sorry if i posted a dumb post guys, but i just had to say what i said, cuz in some cases, im sure that the 16" might very well be lighter.

 

its possible that they might weigh less than the stock acura alloys ~15lbs, and i understand that while plus sizing you might think that there is less rubber and rubber weighs more but you have to remember where the rubber is in relation to the rotation point of the wheel. how many people out there you see with 16" slicks. you dont, there like 13" cause of rotating mass. 15 is a good trade off of size looks handling ect

now im gonna go start up another exhast thread, maybe a couple of "what 1/4 mile time will i run with this setup?" and then maybe a "what tire should i buy?" thread


[Modified by JCushing, 10:47 PM 1/16/2002]

 

The bigger the rim diameter, the more metal that is farther from the center. Think of it... a 3" rim has all the metal close to the center. a 20" dub has the metal that makes the drop center/wide part farther out, PLUS you need more metal to make the complete circle. Thus heavier. Plus the tire. I can dig up some formulas from Dynamics class to clarify, but you're gonna need calculus 3+ to get it. (yes I am a nerd)

 

16's definitely there not as small as 15's just as lighter, Depends on what kind of wheel.

 

Drag racers use a small rim more to be able to run a high profile wrinkle wall slick than for the weight. The traction difference far outweighs the weight.

 

Okay, I get it now. Even though its only an inch longer, that inch puts all the metal where the tire sits on an inch further away from the center, causeing more rotational mass. Aight, i understand now, thanks everybody.

 

LOL! that's very funny

Also, the mass is one thing to consider in a static or inactive/still state. Also need to consider the additional energy needed to start it moving, and then to slow it down or stop it when it is moving -- called rotational inertia -- you know, that thing about "bodies at rest tend to stay at rest... bodies in motion tend to stay in motion... until acted upon by other forces.

 

I autocross.

I use 16"x7.5" Kosei K1s with 215/40/16 Kumho 712s. Total weight is 34lbs. My stock 15s with stock rubber weighs 34lbs.

My 16s are definitely better because they weigh the same, i have wider tires, and the larger diameter wheels help with tire roll-over during cornering.

for autocross (or any race where cornering is involved) a larger diameter tire is preferrable. grassroots magazine did a test using different diameter wheels (same wheel model) for autocross and 17s actually gave the best results.... for drag racing, a wide, smaller diameter wheel is better since you can use bigger slicks.


all of the above are my opinions. i could be wrong