Everything? So the car's weight doesn't matter? <snicker> The total inertia in the wheels might be 5~7% of the car's total inertia.

unsprung wiegth= 4 times sprung wieght good rule of thumb 10 lbs on wheels is 40 lbs as far as acceleration etc goes you should know this jason.

magna the maximum inertia multiplier is 2x not 4x if all the weight is concentrated on the outer edge of the tire. The calculation is based on energy in the angular momentum.

You guys are getting all mixed up with sprung, unsprung, and rotating weight. It's not just that lighter wheels/tires remove unsprung weight (which they do), it's that they remove unsprung rotational weight. Rotational weight is the enemy of acceleration, braking, and handling (wheels have, like any other rotating object, a gyroscopic effect that resists movement along axes other than the current rotation).

For all the talk of wheel weight being the enemy, i have yet to see an objective test comparing wheel weights where the car was significantly (more than .1 sec on a 60sec course) slower with a heavier wheel/tire combo.

I doubt 50 lbs off the car's sprung weight would make much of a difference either, but I think we can both agree it's better to be 50lbs lighter, all other things being equal.

Wheel weight is really a good place to save if you can afford it.

But if you aren't trying to win races... who cares? For the majority of street/track people.... the cheapest wheel that doesn't explode works :p

People who spend the equivalent of the GNP of some small countries racing professionally have concluded that rotational mass at the wheel counts 4x more than non-rotational mass when accelerating and decelerating. I am in no position to discount their findings and will be far more likely to trust their conclusions than that of my fellow dudez on teh enterwebz. aight?

What about those of us that daily drive what is essentially a race car and want to improve ride, response, and control.

It amazes me that even in the Miata crowd so many don't realize the huge benefits of truly lightweight wheels.

Worst mistake I ever made in the ownership of my car was selling my OEM BBS (10lb) wheels. Who cares how much tire you can put on them? The car has never ridden, reacted or handled quite as nicely since.

buy some 10 lbs rpf1's like me goospeed :P only 200 someodd apeice on sale.

I'm hoping this is mainly aimed at gospeed and not the OP.... as there is 3" of wheel width missing :p

yeah its gospeed fwiw i read the 4-1 thing in the norman garret mazda book and it made sense. I didnt know that they made 6uls in 15*10 cool if they had had them back when i bought my wheels i woulda bought 6uls though





















rpf1's are 15*7 newb :P

Yes... but the majority of wheel sizing talked about here has been 15x10... Unless he goes with the 15x9 6ULs.

And they didn't make the 15x10 6ULs... I think it was already mentioned in the thread, Emilio didn't get enough preorders to justify the molds.

4 lbs per wheels is pretty noticeable in terms of ride quality.

I'll let y8s calculate the ratio of energy stored in a 30 lb 24" diameter wheel due to its angular momentum to that of its forward velocity. :)

Hold up! Are the XTRs that I just saw at 949 real? Emilio is playing ball! This is badass.

looks like emilio949 is coming out with a cheap wheel and a 17 wheel.

Awesome. That is about the best possible response Emilio could come up with IMO :bigtu:

Damn, this is the first I've seen of these. Way to play ball. :)

XTR coming Summer 2010 - Low cost gravity cast, 10 spoke design, silver or black
15x9 +20, +36 4x100, 4x114.3, 5x100, 5x114.3 15 -15.4 lbs $109

C

I think they were just added today.

Nice, 6UL for the track and XTR for the street.