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Discussion Starter #21
Yes, less weight in the tire than in the wheel is better for straight-line acceleration, braking, & fuel economy, due to less rotational inertia. HOWEVER your wheel/tire combo of choice in your thread "17's on my 500e" is the opposite:

Stock tire 17Lb, stock rim 18.1Lb (average of staggered-width front & back)
Your tires 18Lb, your rims 17.9L

This may be because those shallower sidewalls you mentioned probably need to be stiffer (heavier) to protect from pothole damage.

Also, your new overall diameter is bigger, for even more added rotational inertia, although the 500e is SO quick that it shouldn't make much difference, & you'll benefit a bit from off-the-line traction, & a lot from cornering traction.
 

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"Heavier than what?"

Heavier than other options.

As you can see from the numbers earlier in this thread:
14s are lightest,
15s are heavier than 14s, &
16s are heavier than 15s.

17s are even heavier than 16s.

Yes, there are some light 17s that aren't as heavy as HEAVY 15s (like stock 500e), but there are other 15s which are even lighter.
Not to be pedantic but the relation between diameter and weight is not linear. There are 18s that are lighter than 16s, just like there are 17s that are lighter than 15s. Material, shape, and fabrication methods all matter. That's why I asked "heavier than what?". Because "17s are heavier" on its own is a false statement, and even with a qualification it's only possibly true.

This thread is great in that respect. Instead of the "smaller = lighter" rule of thumb we have actual weights from viable options. Thanks for that.
 

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Discussion Starter #24 (Edited)
Maybe this is a better way for me to put it: PLEASE PROVE ME WRONG!

I would love for somebody to inform us of a currently available Fiat 500 17", 16", or 15" wheel/tire combo that's lighter than my own 15s!!!

Unfortunately however, when checking more than 63 different available wheels & 223 different tires, the lightest 17s I found were heavier than the lightest 16s, which were heavier than the lightest 15s, which were heavier than the lightest 14s.
 

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This thread is about light wheels.

I said I'll have some info on 17s soon.

You said "17s are heavier".

That is not true. Not always and not even most of the time. It completely depends on the wheel, the width, etc...

If you want to qualify that statement by eliminating all the other factors involved, then I agree with you. Obviously. More of the same metal is clearly heavier. If you want to issue a challenge about finding a 500 wheel that is lighter than the 15s you own, I will politely decline. That was never my point, nor do I care because 15s are not an option I'm considering.

Food for thought though, enkei rpf1s are a pretty light wheel, and there are several sizes in which a smaller diameter is heavier than a larger diameter due to differing widths. **** even the offsets change the weights significantly.

I don't want to argue with you though. This thread is great and the info here is really valuable. Let's not muck it up with bickering.
 

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Discussion Starter #26 (Edited)
This thread is about light wheels...
Food for thought though, enkei rpf1s are a pretty light wheel, and there are several sizes in which a smaller diameter is heavier than a larger diameter due to differing widths...
Not trying to bicker, & I hope I haven't mucked it up yet. I just want to make sure I set the record straight (while still wishing I was wrong):

The lightest available 17" wheel/tire set I could find is significantly heavier than the lightest available in any other size for Fiat 500s. That IS this forum's specific car, & it seems to be the only factor needed to make my statement true.

Anyone please correct me if I'm wrong, but the specs showing at Enkei.com* for that nice light RPF1 you mention show that
the lightest 15 (9.85Lb) is heavier than the heaviest 14 (8.7Lb, 14 is the smallest diameter shown),
The lightest 16 (13.7Lb) is heavier than the heaviest 15 (11.35Lb),
the lightest 17 (14.9Lb) is heavier than the heaviest 16 (14.3Lb) &
the lightest 19 (19.25Lb) is heavier than the heaviest 18 (19.05Lb).
19 is the largest diameter shown.

BUT for other cars you are technically correct that the lightest 18 (16.9Lb), which won't fit a 500** IS slightly lighter than the heaviest 17 (17.25Lb) which also won't fit a 500**.

**5-bolt pattern &/or way too much back-spacing, at the very least (I didn't bother checking tire sizes for fit).

* http://enkei.com/wp-content/uploads/2015/07/RPF1.pdf
 

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Just ordered my new all season set. Listed weights per manufacturers are as folows:

OZ alleggerita 17x7 (4x100) = 14.2lbs*
General G-Max in 205/40/17 = 16.6lbs

Total: 30.8lbs

*This is the tire rack listed weight. The OZ Racing site doesn't show that size and offset combo. Interestingly though they do show a weight for the 17x7 et44...and it's 13.9lbs. If that one clears our rear calipers then it would be lighter than several of the 16" combos listed above.
 

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Try weighing them when they arrive.
I've been told by some suppliers that listed weights are "shipping weights" which include the box and packaging.

Will be interesting to see what you find...
 

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Discussion Starter #29
OZ alleggerita 17x7 (4x100) = 14.2lbs...t. The OZ Racing site doesn't show that size and offset combo. Interestingly though they do show a weight for the 17x7 et44...and it's 13.9lbs. If that one clears our rear calipers then it would be lighter than several of the 16" combos listed above.
REAR CALIPERS, are smaller than front, so they clear even with 14" wheels, as do front calipers except on 500e, Turbo & Abarth.

FRONT calipers of 500e & Turbo require 15s.

Stock rear SWAYBAR mount of Abarth requires 16s.

17" diameter clears everything easily. The problem in this case might be the width/offset combo. As shown in this pic, my 205s on 7" with only 35mm offset barely clear another part (handbrake cable?), & 44mm offset moves the wheel inboard even closer to (hitting?) that part.
1492727465125.jpg
 

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Discussion Starter #30 (Edited)
General G-Max in 205/40/17 = 16.6lbs.
Interesting. I, too, am curious about their actual weight, since there doesn't seem to be a weight spec for that tire at GeneralTire.com, & TireRack lists it at 18Lb, equal to the lightest all-seasons they sell in that size. That would make the total 32.2Lb

My own tires actually weigh a bit more than their TireRack spec.
My wheels match exactly the GoodWinRacing spec.
 

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Interesting. I, too, am curious about their actual weight, since there doesn't seem to be a weight spec for that tire at GeneralTire.com, & TireRack lists it at 18Lb, equal to the lightest all-seasons they sell in that size. That would make the total 32.2Lb

My own tires actually weigh a bit more than their TireRack spec.
My wheels match exactly the GoodWinRacing spec.
This is from generaltire.com...
.
 

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Well now I'm even more curious! Will you be able to weigh them separately when they arrive? (or even together?)
They're being delivered mounted and balanced, so the best I could theoretically get is wheel+tire+tpms+balancing weights....but I don't own a scale. :/ Maybe I'll take one for the team and grab a bathroom scale tomorrow.
 

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I'll chip in $5 for a scale :D
 

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There usually is a bug difference between cast and forged wheels.. I'm surprised that there is no mention of any this.
Maybe forged wheels are so expensive they aren't considered?
 

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There usually is a bug difference between cast and forged wheels.. I'm surprised that there is no mention of any this.
Maybe forged wheels are so expensive they aren't considered?
The stock abarth wheels are forged and ~4lbs heavier each than the cast wheels in the same size (and same design, actually) that I just ordered...

But yes, for me personally the expense of really good aftermarket forged wheels is beyond the point of diminishing returns for the 500e.
 

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Discussion Starter #38 (Edited)
There's at least one relatively new (to me, anyway) subset of reasonably priced but lighter cast wheels with rims formed by spinning after casting, as in "spun aluminum". I believe most, if not all, of the choices I have found & listed above use this process.

For example:

Advanti Storm wheels use it & call it DST (Dynamic Spinning Tech): http://www.advantiwheel.com/advanti-dst/
Enkei RPF1 wheels use it & call it MAT: http://enkei.com/engineering/
Konig Dial-In & Hypergram use it & call it "Flow Formed" (scroll down at http://konigwheels.com/wheels/flow-formed-wheels/hypergram/)
O.Z. Alleggerita HLT seems to also use it & call it "HLT": http://www.ozracing.com/world-of-oz/technology/production/668-hlt
 

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I didn't get a scale because I'm lazy but the alleggeritas did come with these tags on them and I feel like Sergio is a pretty straight shooter. Anyone who weighs a painted car wheel to the thousandth of a pound is alright by me....
.
 

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Discussion Starter #40
It's the tires I suspect are heavier than the spec, which would add rotational inertia. If you do before & after 0-60 runs it will tell us if there's any significant difference, if you can do it at about the same ambient & motor/batt temperatures, & charge level.
 
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