Can you feel 5-7 pounds of wheel weight per corner? 20 lbs total

[Go Frogs]

Originally Posted by leevanf

How does 5-7 pounds per corner less of wheel and tire weight savings really feel like? I mean i am sensitive to an empty gas tank. So would i feel it especially over potholes and bumpy roads?

You will probably feel it initially, but the difference will fade over time and then it becomes the new normal until you go back the other direction.

Obviously, a lighter wheel/tire package will respond better, or will allow the suspension to respond better to bumps and things. Of course this could be offset by bigger brakes, but that is for another discussion.

Check out articles on Sprung vs Unsprung weight plus articles on rotating mass.

Once you've read enough you should be able to come to your own conclusions and you will see several different theories/formulas/ratios, but the science is the same.

From physics class, IIRC, it is easier to start/stop a lighter wheel, than a heavier wheel...plus, it is easier to start/stop a wheel with most of the weight closer to the center versus further away from the center.

Reducing weight where you can is always a good thing.

[nikitopo]

Originally Posted by leevanf

Looking at the TWS T66F 16x7, on 225/50 or 205/55 tires. Wheel is already 10lb savings vs stock. But tired are nearly 3 lbs heavier so its about 7 lbs net


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Nice option. Go for it!

Just keep in mind that this size is for ultra high performance (UHP) or semi-slick tires. Otherwise, you'll lose cornering performance because of the high profile!

[ZDan]

This year at Palmer I had two sets of wheels/tires:
235/40-17 NT01 on 17x9 +40 6UL wheels, 36 lb. wheel+tire
225/45-17 RE71R on 17x7.5 +45 factory wheels, 42 lb. wheel+tire

I ran one practice session each on the morning of the time trial day. Went a couple/few tenths faster on the NT01/6UL later in the first session, then slightly slower but with quickest laps earlier in the 2nd session on RE71R/factory wheels.

It was very overcast and rain was forecast, so I left the heavier RE71R/factory wheels on for my TT, running ~ 4 gallons less fuel than I would have with the NT01/6UL setup to stay close to my minimum weight. TT was totally dry, but I went another 0.2 seconds faster vs. practice on the lighter wheel/tire setup. Won TT over another BRZ on Toyo RRs

Could I *feel* the difference between 42 lb. per corner and 36 lb/corner? Honestly, no, not really... I'm sure any feel differences were more due to tire and wheel width differences anyway.

TL/DR: I wouldn't worry too much about wheel or tire weights within reason...

[leevanf]

Originally Posted by nikitopo

Nice option. Go for it!

Just keep in mind that this size is for ultra high performance (UHP) or semi-slick tires. Otherwise, you'll lose cornering performance because of the high profile!

Oh man, but the car is just a DD. No track! Would you recommend i go 17x7 for T66Fs? But they will no longer be hubcentric. Unlike 16/18s. I dont know why but im OC about that!


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[leevanf]

Originally Posted by ZDan

This year at Palmer I had two sets of wheels/tires:
235/40-17 NT01 on 17x9 +40 6UL wheels, 36 lb. wheel+tire
225/45-17 RE71R on 17x7.5 +45 factory wheels, 42 lb. wheel+tire

I ran one practice session each on the morning of the time trial day. Went a couple/few tenths faster on the NT01/6UL later in the first session, then slightly slower but with quickest laps earlier in the 2nd session on RE71R/factory wheels.

It was very overcast and rain was forecast, so I left the heavier RE71R/factory wheels on for my TT, running ~ 4 gallons less fuel than I would have with the NT01/6UL setup to stay close to my minimum weight. TT was totally dry, but I went another 0.2 seconds faster vs. practice on the lighter wheel/tire setup. Won TT over another BRZ on Toyo RRs

Could I *feel* the difference between 42 lb. per corner and 36 lb/corner? Honestly, no, not really... I'm sure any feel differences were more due to tire and wheel width differences anyway.

TL/DR: I wouldn't worry too much about wheel or tire weights within reason...

Wow buddy thanks for the share! But i was looking more in terms of DD comfort! Stop and go/acceleration


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[jflogerzi]

Hubcentric rings... Not sure why you want to spend so much money for just a DD...

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[Stang70Fastback]

Full disclosure: I haven't read all the replies.

I used to run 16" steelies as my winter set. At the time my summer set were the stock STI wheels that came with the Series.Blue. That meant the summer wheels were 18.4 lb, whereas the winter wheels were something like 24 lb. The difference was definitely noticeable at highways speeds, where the gyroscopic force of the heavier wheels added resistance to the steering. As a result, the steering felt heavy at speed, which meant the car felt less willing to change direction.

[leevanf]

Originally Posted by jflogerzi

Hubcentric rings... Not sure why you want to spend so much money for just a DD...

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Im planning to keep a brz in my life always lol, so i may end up selling this or building an autox / track toy later on. So im guessing if im buying rims ill do it right the first time it should last forever


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[leevanf]

Originally Posted by Stang70Fastback

Full disclosure: I haven't read all the replies.

I used to run 16" steelies as my winter set. At the time my summer set were the stock STI wheels that came with the Series.Blue. That meant the summer wheels were 18.4 lb, whereas the winter wheels were something like 24 lb. The difference was definitely noticeable at highways speeds, where the gyroscopic force of the heavier wheels added resistance to the steering. As a result, the steering felt heavy at speed, which meant the car felt less willing to change direction.

Your fujitsubo video on youtube. 10% of your views were probably all me lol!


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[Adam_L]

It sounds like you want to go with a 16" wheel then. I recommend a 195 / 55- 16 , or possibly a 205 / 50- 16. Stick to a 16x7 wheel....nothing wider ( no 16x8, etc). If it rains a lot where you live, get a good rain tire.

I know a couple of mega-high performance Forged alloy wheels in 16" what weigh about 11 pounds per wheel , but even if you can get a 16" forged or cast, at about 13 to 13.5 pounds per whee, at a good price go for it. Could also get Forged lug nuts, like Buddy Club…. very light.

Also, I'd say doing a nice aftermarket wheel tire is one of the better ways to mod your car after the fact ( oem), in that it's a combination of performance ( lower weight + a tire that suits your needs more so and can help in stopping distance-safety) plus looks / styling , all in one package

[extrashaky]

I felt a difference going from stock rims to RPF1s, but I'm almost certain it was confirmation bias. I suspect most of the people posting that they feel a difference are experiencing the same confirmation bias. You want it to be an improvement. You expect it to be an improvement. So you feel an improvement.

In related news, I'm addicted to placebos. I would quit, but it wouldn't matter.

[g e]

Originally Posted by Stang70Fastback

Full disclosure: I haven't read all the replies.

I used to run 16" steelies as my winter set. At the time my summer set were the stock STI wheels that came with the Series.Blue. That meant the summer wheels were 18.4 lb, whereas the winter wheels were something like 24 lb. The difference was definitely noticeable at highways speeds, where the gyroscopic force of the heavier wheels added resistance to the steering. As a result, the steering felt heavy at speed, which meant the car felt less willing to change direction.

Winter tires have more aggressive tread and also squirmier for better cold temperature grip. That contributes a lot to the change in steering dynamic

[Stang70Fastback]

Originally Posted by g e

Winter tires have more aggressive tread and also squirmier for better cold temperature grip. That contributes a lot to the change in steering dynamic

Correct. But I'm not talking out steering sharpness, or turn-in lag as a result of tread deformation and sidewall deflection. I'm talking about steering weight.

[no1]

I think people are well aware of certain factors: Flywheel effect means acceleration and braking is faster/slower. Gyroscopic effect makes turning easier/harder. These, combined with unsprung weight, also affect contact on an uneven road.


But one thing I never see or hear mentioned is weight distribution. A smaller wheel has better weight distribution. A heavier 16" wheel will outperform a lighter 18" wheel pretty easily. (Yet 16's are smaller, so they will tend to be lighter anyhow, and cheaper.) It minimizes all those problematic effects above.


This is my own reasoning/hunch as I don't have any solid empirical data to back it: Even comparing traits of the same diameter, a 17" cast to a 17" roto-formed wheel, for instance, the cast will tend to have a thicker barrel. (Right?) That means more of the mass is distributed toward the edges which is the worst place for weight to be, because it has higher leverage during rotation. That maximizes all the problematic effects listed above. Therefore, I think roto-formed wheels are more valuable, even if their overall weight is equal to a cast wheel, for having such better distribution. Heavier spokes and hubs are, by comparison, not nearly as critical. (They're unsprung, yes, but not as much of a factor in the even worse flywheel or gyroscopic effects.)



I wish we had some measurements to compare the barrel weight and thickness of roto-formed vs. forged vs. cast, but it's not even easy to get the overall weight, sometimes.