Benefit of lightweight rims?

[Brady]

i think im done with the saws i was looking at both the gold sportmax 962 and the ssr gt2 the ssr is like sixteen pounds while the sportmax are about twenty five but they are also about eight hundred dollars cheaper a set my question is how much of a difference can one expect to see with the lighter wheels?

 

[IJ.]

Quicker to accelerate better braking less unsprung weight means the suspension has an easier time controlling wheel travel and you make the wheel shop rich repairing then replacing them each time you ding one on the street

 

[Doward]

lmao, yeah - Ian's hit all the major points

Lighter wheels are easier to change, too! Less lifting

 

[figgie]

simple physics!

It applies to all object that rotate. Wheel/rims are no exception.

 

[emiliorescigno]

Lighter wheels are better in every way you can think, except price.

While you're reseaching, look up 5zigen FN01R-C's, they're cheap(ish), light(ish), and available in bronze!

 

[Rennat]

the only problem is if you get lighter wheels, you normally get a wider rim, say an 8''/9'' in the front, and 9-11'' in the back... with those bigger rims, you put bigger tires, which weigh more... just something to think about.

When i weighed my stock saws with 225 kumoh's it was around ~48lbs if i remember...
the 5-zigens i had which were a 17x8 with 235's weighed like ~45lbs... so i only saved 12lbs all around, and all i felt was a much rougher ride. So dont be TOO concerned with all of the hype about super ultra jdm light wheels, get something you like and that appeals to you.

 

[Big Rob]

who doesn't want to reap the benifits of wider tyres?

 

[BorHor]

Light wheels FTW

 

[ms07s]

It's not a ugly-ass sawblade.:biglaugh:

 

[BorHor]

Saws are sweet for taking a Supra to the junk yard

 

[BorHor]

Oh and Brady if you find something you like PM me and I'll see if I can hook it up locally

 

[blake]

Ok so you know how when you're braking on an uneven or broken or rippled bit of asphalt (not sandy/gravely) and if you have ABS it's cycling on and off rapidly as your tires gain and lose grip? Lighter wheels keep the tires pressed against the road more of the time, or less likely to break free in the same situation.

Basically, you have 3 'numbers' to be concerned about. The weight of the 'sprung mass' (the tires, wheels, brakes, partially the suspension) the weight of the rest of the car, and the spring rate of the springs (let's leave out dampers for now).

Imagine the Supra is floating in zero-G. The springs are compressed to normal ride height by some mechanism. But then you release that mechanism and the wheels/etc entirely. The wheels get flung away from the car into space and in return the car goes the other way.

The heavier the wheels the more the car moves and the less the wheels move. The lighter the wheels the more the wheels move and the less the car moves.

The springs are there to move the wheels to keep them in contact with the ground. The less the wheels weigh, the more successful the springs are.

That was a bit of a wandering explanation with a few different angles. Hopefully one of them 'struck' you and it kinda makes sense now.

P.S. Nitpickers leave me alone. Just trying to give the right idea, not get my math right

P.P.S. I really like the SSR GT2s as well, but likewise my second choice is the FN01R-C (I think I got that ridiculous model code right this time).

 

[7MsuprO]

When i weighed my stock saws with 225 kumoh's it was around ~48lbs if i remember...
the 5-zigens i had which were a 17x8 with 235's weighed like ~45lbs... so i only saved 12lbs all around

Not to nitpick but rotating mass isn't the same as static mass. Shedding 12lbs on your wheels is worth more than you stopping fast food consumption and losing 12lbs for example. Then again, in the real world I guess perception is everything.

 

[The Evil Twin_7MGE]

Not to nitpick but rotating mass isn't the same as static mass. Shedding 12lbs on your wheels is worth more than you stopping fast food consumption and losing 12lbs for example. Then again, in the real world I guess perception is everything.

Yeah, not only is there the effect of accelerating that mass forward, but the effect of radial acceleration too. Not that it hasn't been said before, just putting it in different terms. I think the effect of lost wheel mass is something like 4x the effect of lost static mass, but don't quote me on that, I haven't done the math myself yet.

*edit* don't listen to that 4x bullshit, I'm doing the math, it's like 1.5x

 

[IJ.]

PMoI

 

[7Mboost]

Don't get those Sportmaxx 240 strech tire rice, get the nice SSR's, I hate when mk3 owners cheap out on wheels.

 

[Keros]

I read on this forum somewhere the ratio of rotating mass vs static mass is something like 1:10... losing 1lb of rotating mass is like losing 10lbs of static mass in terms of acceleration and braking.

Most 275 tires I've looked at weigh in around 25lbs... Keeping in mind that the tire is furthest from the center of rotation (forgive me stating the obvious), having a light tire on a heavy rim may be more beneficial than a light rim with a heavier tire. The downside is it's easier to choose the weight of the rim vs the weight of the tires, lol. Something to think about anyway.

Light rims with light tires are FTW performance wise... but a stout rim that you like with a light tire is probably the best way to go for everyday use.

 

[Brady]

i never thought of tires themselves being that heavy

that figure rennat said - fn01rcs being 45 lbs with 235's? 45lbs x 4?! jeez

 

[The Evil Twin_7MGE]

I read on this forum somewhere the ratio of rotating mass vs static mass is something like 1:10... losing 1lb of rotating mass is like losing 10lbs of static mass in terms of acceleration and braking.

I just did some math. The energy of a stationary 23lb wheel rotating at 60mph is 24311.9 newtons (K rotating=Iw^2), and the energy of a 23lb mass moving at 60mph is 48120.2 newtons (K = mv^2). So unless I'm missing something, and I'm sure friction and drag have an effect but not THAT much an effect, losing 10 pounds off a rim is like losing 15 pounds of stationary mass.

*edit* actually, that doesn't consider the thickness or weight of the tires, but it wouldn't really change it much.

 

[BorHor]

i never thought of tires themselves being that heavy

that figure rennat said - fn01rcs being 45 lbs with 235's? 45lbs x 4?! jeez

I dont think mine are that much.. I should weigh them one day though.