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Smaller Wheels Don't Always = Less Weight, Taller Tire Adds Weight

Capri to ST

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#1
When looking at how much weight you save with different wheel options, you don't automatically save more weight by going with smaller diameter wheels, because you have to consider the weight of the wheel/tire combo together in my opinion. Smaller lighter wheels can have correspondingly heavier tires because of taller sidewalls if you want to keep the same overall diameter, which I do.
Here are the calculations I made when deciding to get stock size 17 x 7 Pro Race 1.2's:

Stock wheel-22.5 lb + stock Potenzas@ 19 lb= 41.5 lb TOTAL WHEEL/TIRE COMBO
17" PR 1.2's-17.4 lb + stock Potenzas@ 19 lb= 36.4 lb "
16" " -16.4 lb + sample 205/45-16's@21 lb= 37.4 lb "

My sample 205/45-16's from Tire Rack were made looking at summer performance tires. Most were 21 lb. Tire Rack doesn't show the stock Potenzas in any 16" size. One or two of the comparison 16's were lighter, so you'd save a pound or so by going to 16's with those few tires, but these calculations surprised me a bit, and for me helped me decide to stay with 17's. I didn't spend as much time on 15's because I wasn't considering them, but a quick look at them led me to some similar conclusions.
I also wanted to keep the quick agile handling and was willing not to soften the ride a bit with a slightly taller sidewall to keep that handling goal. Of course, some want to soften the ride and then going to 16's or 15's may be a way to that, but I'm just talking about weight here. This surprised me a bit because I had just assumed that smaller wheels would save overall weight.
You can also get into more esoteric considerations of how close the rotational weight is to the axle with different setups. I'm not good enough at physics to know too much about that, but my guess is that you would want the slightly heavier 17" PR 1.2 closer to the center of rotation where it's easier to spin, over having the heavier 16" tire farther away from the center in the 16" setup, where it's theoretically harder to spin.
Just some things I thought about to help others in their decision process.
 


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#3
I think part of the problem is the Pro Race 1.2s aren't that light.

I think the 15x8s are like 14.5 or 15lbs but you can get Konig Helix in 15x8 that weight 11.2 and 205/50-15s still only weight 20-21lb. RPF1s should be like 13.5lbs for a 16x7 for example.
 


M-Sport fan

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#4
Yes, GREAT points![thumb]

But of course, the wheel 'weight weenies' (used as a term of endearment, NOT a derisive one, since they are CORRECT by the laws of physics, to desire this!) will come back/respond hard with the fact that one can choose a MUCH MUCH lighter wheel than the one you cite, yes even if it means HAVING TO drill your hubs for a 4x100 PCD, even if you do not want to do that job, and everything that comes with it.
 


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#5
You just need to find a lighter 205/45R16. The recently released tires are going to be much lighter than old ones like the comp-2 or RE760. The Firehawk Indy 500s are 19 lbs. The Continental ExtremeContact Sports are 18 lbs. Also, there are really no good tires left in our stock size besides the RE050As, and they are way overpriced with shitty treadwear.
 


OP
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Thread Starter #6
I think part of the problem is the Pro Race 1.2s aren't that light.

I think the 15x8s are like 14.5 or 15lbs but you can get Konig Helix in 15x8 that weight 11.2 and 205/50-15s still only weight 20-21lb. RPF1s should be like 13.5lbs for a 16x7 for example.
I wanted a stock 4 x 108 bolt pattern, didn't want to go to the hassle and expense of converting to a different one, and I don't believe either of those wheels comes in 4 x 108. The Pro Race 1.2's also come with the stock hub bore, and it's nice not having to use hubcentric rings.
 


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#7
Yep, definitely can't blame you. My fiesta ST is my daily, not my fun car, but I still find myself messing with it and trying to figure out how to fit the most tire. Thanks for putting the research up here.
 


M-Sport fan

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#8
The Pro Race 1.2's also come with the stock hub bore, and it's nice not having to use hubcentric rings.
+1! [thumb] I could not agree with you more on that point, even though most on here would say it is NO problem using them, and some would even say the larger hub bore makes their wheels lighter, despite the added weight of the rings. LOL
 


PCA-1

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#10
I wanted a stock 4 x 108 bolt pattern, didn't want to go to the hassle and expense of converting to a different one, and I don't believe either of those wheels comes in 4 x 108. The Pro Race 1.2's also come with the stock hub bore, and it's nice not having to use hubcentric rings.
...and you also can have generous color options and custom offsets. ;)
 


neeqness

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#11
There are so many tires with different weights. Of course if you pick a heavier tire to pair with a lighter wheel, you tip the balance in your favor...if your intent is to say lighter wheels are not always lighter. But if you used a lighter tire the results will be different and in general the taller difference in tire will usually be lighter than the size difference in the wheel.

But really though, no need to compete over the weight issue. I know all things considered I would go with 15" even if it did mean that my overall combo was slightly heavier. I just like the look, feel, and everything else about it better than a 16" or 17" wheel. I suspect most of us feel the same regardless which wheel we prefer.

Don't get me wrong, I dont dislike the 17" wheel or anything I just "prefer" a 15" for the full package deal...not just because it is lighter. So this argument makes little difference. I could just find a lighter tire if I really cared about it or use a slightly lower aspect or whatever to make things work out best for my preference.

I think people will ultimately choose whatever they like the most regardless except perhaps the most race oriented drivers...which may be the minority on this forum. That said I do take note of all the tips that those drivers offer as while I may not be as extreme in my efforts to increase performance, I do appreciate a better performing car.


Sent from my LG-H918 using Tapatalk
 


Waterfan

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#12
True, but absolute weight is not the only factor. Larger wheels concentrate the weight towards the outer circumference which adds to the rotational forces relative to a smaller wheel package of the same absolute weight.
 


ron@whoosh

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#14
With the O.E. weight of 41lbs per wheel and tire compared to the Enkie RPF-1/205/40R16 Falken Azenis RT615K+ at 32lbs. The reduction of nine pounds per corner is very noticeable.
this ^^^^^


agree 1000%
 


OP
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Thread Starter #16
The weight is great, but when I looked at Enkei's site, it looks like it doesn't come in the oem 4 x 108 bolt pattern which I was looking for.
 


Waterfan

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#19
16" RPF1 13.4 lb + sample 205/45-16's@21 lb= 34.4 lb [grinking]
On the subject of tire weights, the lightest 205/45-16s I have found are:
CONTI ECS - 18 lbs
BSTONE RE71R - 19lbs
FSTONE Indy 500 - 19lbs
SUMI HTR ZII - 19lbs
TOYO R1R - 19lbs

(My current, cheap and decent BFG SC2 are 21 lbs. Switching to Indy 500 soon.)

(For reference 205/40-17 OEM 050A are 19lbs)
 


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#20
While doing research for tires, I made a spreadsheet for different sizes (205/40-17, 205/45-17, 215/40-17, 205/45-16, 205/50-16) to compare section width, tread width, weight, etc. across different tires of the same size. You always hear that xxx tire runs wide or yyy tire runs narrow, etc, and I never really realized it until I put it on paper in front of me. If anyone knows how to upload a file to share I'll be more than happy to do so...there's another spreadsheet I did with gearing and tire sizes too.
 


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