TRD Wheels on a 2018 BRZ

[rvoll]

Originally Posted by mrg666

Cut the crap man! Drive with your skinny tires as much as you want. My tires are not extra wide, they are as wide as required. Save your stupid stories for yourself.

215's on a car as light as the BRZ/86 are NOT skinny tires and are, in fact the REQUIRED size for this car. I do agree with the bulk of you, however, that the OEM Primacy tires are not performance oriented.

[mrg666]

Originally Posted by rvoll

Of course friction is a related to contact patch, pressure, and compound. However, these physics teachers (not car experts who have done significant testing). They have some assumptions that are just wrong (which proves they don't know a lot about cars). One of these assumptions is that wider tires have softer compounds. If you take the same brand, let's say Michelin Pilot Sports, they use the same exact compound on both narrower and wider tires. They also take a static, rather than a dynamic analysis of tire functionality. Narrower tires heat up more on the track which makes them stickier. Wider tires create more of an air gap between the pavement and tire as the speed increases. Turning a wider tire creates more friction and thus is not as reactive. We call this the law of unintended consequences. (And yes, I majored in math, with minors in physics and chemistry in college.)

I was young once and thought I knew everything. Now that I'm over 70, I've learned that you not only need theory, but you need actual proof that's not based upon human fallibility, but actual results.

Physics is physics who ever the source is. And I don't see any problem with physics teachers. You just can't have any conflict with physics and be correct at the same time. I am done here.

[switchlanez]

Originally Posted by rvoll

I don't want a black, or near black wheel.

Then why are you dismissing the non-black wheels I suggested and only considering the near black TRD 17"?

Originally Posted by rvoll

I'm not racing the car

Then why do you actively perpetuate discussion towards maximizing performance?

Originally Posted by rvoll

It will look great...7.5 inches wide, and has an offset of 43 which will make the wheels a bit more flush

Oh are you concerned about looks? The 18x8 +44 non-black wheel I posted is more flush, feels notably better on throttle, and fits "reasonable" 225 tires. The concentric outline on an 18" runs more parallel with the wheel well arc than a 17". Basic math.

Originally Posted by rvoll

I'm going to use the car for touring

Originally Posted by rvoll

I'm over 70.

That might bias why you're defending narrow 17s with more sidewall so hard. And then show concern for looks yet those who choose 18" wheels (like Toyota and Subaru offer from the factory) you need to label as ricers. So I need to label you a pretentious a-hole. I see more productive discussion when the wise share knowledge in earnest and save the waxing poetic of how knowledgeable they are.

[rvoll]

Originally Posted by switchlanez

Then why are you dismissing the non-black wheels I suggested and only considering the near black TRD 17"?

Then why do you actively perpetuate discussion towards maximizing performance?

Oh are you concerned about looks? The 18x8 +44 non-black wheel I posted is more flush, feels notably better on throttle, and fits "reasonable" 225 tires. The concentric outline on an 18" runs more parallel with the wheel well arc than a 17". Basic math.

That might bias why you're defending narrow 17s with more sidewall so hard. And then show concern for looks yet those who choose 18" wheels (like Toyota and Subaru offer from the factory) you need to label as ricers. So I need to label you a pretentious a-hole. I see more productive discussion when the wise share knowledge in earnest and save the waxing poetic of how knowledgeable they are.

Please re-read my posts. I said I liked your rim, but when I priced it, I saw it cost $700 which was not cost justifiable for my particular use. Secondly, the 18x8 wheel is NOT more flush -- in fact, they have the same level of flushness almost exactly. Do the math. You are certainly right that the 18's look better on the car -- you'll see no argument from me on that. But, the 17's will ride better because it has a larger sidewall. Lastly, do you really consider 215's to be narrow? Really? For such a light car?

From a performance perspective for MY particular use, I get no real benefit from wider rims and tires. And again, a-hole comment aside, I said I LIKE your rims. They really look good on the car. I do honestly believe that people put wider rims and tires on a car to make it look more than it is. We have a 200 hp car, not a 500 hp car. The first thing "ricers" do is put on wide tires and lower the car. Next, they change the exhaust to make more noise. If it walks like a duck......

[switchlanez]

Originally Posted by rvoll

Please re-read my posts. I said I liked your rim, but when I priced it, I saw it cost $700 which was not cost justifiable for my particular use. Secondly, the 18x8 wheel is NOT more flush -- in fact, they have the same level of flushness almost exactly. Do the math. You are certainly right that the 18's look better on the car -- you'll see no argument from me on that. But, the 17's will ride better because it has a larger sidewall. Lastly, do you really consider 215's to be narrow? Really? For such a light car?

From a performance perspective for MY particular use, I get no real benefit from wider rims and tires. And again, a-hole comment aside, I said I LIKE your rims. They really look good on the car. I do honestly believe that people put wider rims and tires on a car to make it look more than it is. We have a 200 hp car, not a 500 hp car. The first thing "ricers" do is put on wide tires and lower the car. Next, they change the exhaust to make more noise. If it walks like a duck......

Thanks for the compliment. I have been reading your posts. I see a lot of gloating and had to call it out.

215 is narrow relative to the size recommended by the OEM on their optional 7.5" wheels. 225 > 215. That's straight inequality math, not opinion.

Assume stock 17x7 +48 as baseline to compare flushness:
TRD 17x7.5 +43: (0.5"/2)*(25.4mm/inch) + 5mm = 6.35mm + 5mm = 11.35mm more flush than stock
TWS 18x8 +44: (1"/2)*(25.4mm/inch) + 4mm = 12.7 + 4mm = 16.7mm more flush than stock

TWS is 5.35mm more flush than TRD. That's more than a spacer. And millimeters count (I run a 3mm spacer for clearance).

So you're saying a ricer changes their wheels for aesthetic purposes and there's a performance hit (though it can be neglected because their purpose is generally not for racing). They just want to cruise in style. Sounds awfully familiar...

Originally Posted by rvoll

I'm going to use the car for touring and not racing

Originally Posted by rvoll

So the difference primarily is in looks -- which are important to many of us. The color of the wheel and that it is more flush makes the car look better IMO.

Spoken like a true ricer. I'd like to see you get those TRD wheels (either 215 tires with sidewall stretch like ricers do or 225 with a performance hit like a ricer) so I can call you, by your definition, a ricer.

I selected wheels/tires that flow with the body lines and don't care if the car is too light for its tires (though it's within 100 lbs. of a base 987 Cayman with similar power and same staggered tire widths). And tuned to the fully stock and quiet exhaust system. Toyota determined an optimal height for this car through prototype testing and VLN races then raised it for passenger vehicle mass production purposes (to clear city nuisances like driveways, parking blocks, etc.). Following 86 Chief Engineer Tetsuya Tada's height recommendation I lowered it on OEM parts so it "walks like a duck":

[nikitopo]

Originally Posted by mrg666

The stock size is 215/45-17. So did you buy used to get the car with 205/55-16 tires?

No, I didn't buy used. I am located in Europe and at some time we had two trim levels. One trim was called Sport which had much less weight and it had the 205/55 R16 tires and the other was called Premium with more comfort features and the 215/45 R17 tires. The purpose of the Sport trim was to use it more on track and have semi slick tires. The Premium trim was better equipped for day to day usage and the increase of wheel and tire size was because you wouldn't use a semi slick tire. For some reason in US you got only the Premium level. It was called Premium and Limited, but in a sense the one was just a bit more premium than the other.

Originally Posted by mrg666

Physics is physics who ever the source is. And I don't see any problem with physics teachers. You just can't have any conflict with physics and be correct at the same time. I am done here.

Physics is just a science to model reality. If your model is wrong, then you change the model not the reality. This is why as noted before we need experiments and measurements to confirm the model.

[funwheeldrive]

Originally Posted by switchlanez

You seem like a sensible guy and Toyota has offered a sensible, balanced package fitting for your needs.

And guess what's in it:

Wheels
TWS T66-F
Size (F) 18x8.0J INSET44
Size (R) 18x8.0J INSET44

Tires
Michelin PILOT SUPER SPORT 2
Size (F)225/40/18
Size (R)225/40/18

This is just my opinion, but 18" wheels look wrong on a BRZ/86. Too much wheel/tire for such a small car. I'm sure they are nice wheels, but that's not the look I would want for my car.

[switchlanez]

Originally Posted by funwheeldrive

This is just my opinion, but 18" wheels look wrong on a BRZ/86. Too much wheel/tire for such a small car. I'm sure they are nice wheels, but that's not the look I would want for my car.

In terms of performance I never denied 17" could be better. Quoting myself from 2012:

Originally Posted by switchlanez

The gymkhana Exmotion BRZ (same driver as the BRZ GT300) has 17" Volks and the VLN FT-86 from 2011 and this year's title-winning VLN GT 86s had 17" BBS wheels. 17s are the optimal wheel with which this car was engineered for performance plus comfier; 18s err towards aesthetics.

But in terms of looks, Toyota and Subaru would disagree with you:









And the list goes on. Then there's the Griffon 86 tuned by TRD to set a Tsukuba lap record. 18x9.5 TWS wheels and 265/35 tires but weighed only 2161 lbs.
http://www.trdparts.jp/griffon/spec.html

[nikitopo]

Originally Posted by switchlanez

+Then there's the Griffon 86 tuned by TRD to set a Tsukuba lap record. 18x9.5 TWS wheels and 265/35 tires but weighed only 2161 lbs.

And massive down force

I've ever seen an NA car in similar tire dimensions that had in Tsukuba 4,300 Newtons of down force.

[rvoll]

Originally Posted by switchlanez

215 is narrow relative to the size recommended by the OEM on their optional 7.5" wheels. 225 > 215. That's straight inequality math, not opinion.

Assume stock 17x7 +48 as baseline to compare flushness:
TRD 17x7.5 +43: (0.5"/2)*(25.4mm/inch) + 5mm = 6.35mm + 5mm = 11.35mm more flush than stock
TWS 18x8 +44: (1"/2)*(25.4mm/inch) + 4mm = 12.7 + 4mm = 16.7mm more flush than stock

TWS is 5.35mm more flush than TRD. That's more than a spacer. And millimeters count (I run a 3mm spacer for clearance).

Can you show me where the OEM recommends 225's vs 215's on 7.5 rims? I doubt they would do that creating a speedo error. In fact, if you go to the Subaru site, they list 215's for all wheels including the performance package and tS which have 7.5 wheels. Look it up on their site.

Secondly, your calculation is in error. This is an example that mirrors the physics teachers you quoted before who lack real world experience and thus don't understand dynamic analysis. Wheels carry something called "tires". Tires stick out more than the wheels. Thus, it doesn't matter what wheel size you use because the poke will be based on the part of the tire/wheel that sticks out the most. You have a precise calculation but it does not mirror the real world. In fact, with the same width tire, the TRD rim will, in reality, be slightly more flush than your rim because of the offset. By the way, I see no reason not to put a 225 on either rim as it is well within the tire specs. That being said, if you put 215 on the 7.5" rim and a 225 on the 8" rim, then the section width difference is 0.4"/2*25.4 or 5mm. In that case, your 225 would be 4mm more flush. Because of the section width, however, if I do get the 7.5" rims, I'll probably also go for the 225's because they are a slightly better fit. And thus, I'll be a little more flush than you.

And again, I think your wheels look great!!!! I liked them so much I did a search to see the price. I wouldn't have done that otherwise. If they would have been in the price range of the TRD wheel, I might well have been convinced. However, they cost twice as much and that is hard to justify given that they would both be almost just as flush....

[rvoll]

Originally Posted by mrg666

Physics is physics who ever the source is. And I don't see any problem with physics teachers. You just can't have any conflict with physics and be correct at the same time. I am done here.

With physics, as with math, you can be precisely wrong. The physics teachers utilized a limited number of variables to come to their conclusions. They did not take into account dynamic events like tire temps, wheel weight, drag coefficients, downforce stats, how low the car is and handling characteristics during cornering. There are so many variables, that the only way to come to a real world conclusion is with real world experience, which these guys did not have. I'm sure if I actually got these guys out on a track, they would be convinced their analysis was flawed.

There are some situations where wide wheels make sense. For example, at high speeds you could have greater downforce which would affect the contact pressure. If you have more hp on a dry pavement, wider wheels "might" help to prevent wheel spin. But on a track with long straightaways, very wide wheels will kill you both with weight and resistance.

All of that said, most of us don't race our cars at high speeds. Because of that, it is much harder to argue for lower profile, wider wheels because they reduce comfort and don't fare as well on roads that are not extremely flat. Again, tire selection makes a huge difference for most of us who don't race our cars.

The reason many BRZ's are pictured with large, wide wheels is because that just looks sexy. A few years ago, one of my neighbors had a slammed Miata with 19" wheels. It looked sexy, but he had to replace his front bumper at least twice a year, could not ride on bad roads, and had to sit on a pillow because his butt hurt so much on rides longer than 15 minutes.

And you are right, my problem is not with physics, but with the analysis and variables thereto....

[fatoni]

Originally Posted by rvoll

Wheel width determines the limits of tire size. Go to tire manufacturer specs and it will tell you appropriate wheel sizes for that specific tires. Go outside the bounds of those recommendations, and you could be in trouble. So yes, we are talking about what matters in wheel width. Do your research.

Originally Posted by rvoll

Can you show me where the OEM recommends 225's vs 215's on 7.5 rims? I doubt they would do that creating a speedo error. In fact, if you go to the Subaru site, they list 215's for all wheels including the performance package and tS which have 7.5 wheels. Look it up on their site.

Secondly, your calculation is in error. This is an example that mirrors the physics teachers you quoted before who lack real world experience and thus don't understand dynamic analysis. Wheels carry something called "tires". Tires stick out more than the wheels. Thus, it doesn't matter what wheel size you use because the poke will be based on the part of the tire/wheel that sticks out the most. You have a precise calculation but it does not mirror the real world. In fact, with the same width tire, the TRD rim will, in reality, be slightly more flush than your rim because of the offset. By the way, I see no reason not to put a 225 on either rim as it is well within the tire specs. That being said, if you put 215 on the 7.5" rim and a 225 on the 8" rim, then the section width difference is 0.4"/2*25.4 or 5mm. In that case, your 225 would be 4mm more flush. Because of the section width, however, if I do get the 7.5" rims, I'll probably also go for the 225's because they are a slightly better fit. And thus, I'll be a little more flush than you.

And again, I think your wheels look great!!!! I liked them so much I did a search to see the price. I wouldn't have done that otherwise. If they would have been in the price range of the TRD wheel, I might well have been convinced. However, they cost twice as much and that is hard to justify given that they would both be almost just as flush....

surely you, with all your infinite knowledge, cant be suggesting its possible for a single tire width to be appropriate for multiple wheel widths. youve spent the last several days trying to convince me otherwise.

[rvoll]

Originally Posted by fatoni

surely you, with all your infinite knowledge, cant be suggesting its possible for a single tire width to be appropriate for multiple wheel widths. youve spent the last several days trying to convince me otherwise.

I see you're trying to be too cute by half... Again, the width of the wheel determines the LIMITS of the tires you can put on them as I said in my post. When you go beyond those limits, you either squeeze or stretch the tire. Those limits are set by the tire manufacturer to guarantee that the tire will not fail on a rim. If the tire does fail, and you have gone outside of those limits, you are liable for the tire failure, not the manufacturer. So for the Pilot Sport 4S, for example, you'll see the limits posted on the following chart:

https://www.michelinman.com/upload/m...t-sport-4s.pdf

So for a 215/45/17, the OEM spec, you can put it on a 7-8" rim. For a 225/45/17, you can put it on a 7-8.5" rim. But if I wanted to put on a 245/40/17, I could not put it on a 7.5" rim. The narrower the sidewall, the more limited your rim range will be. So on my 7.5" rim, I could go up to 235/45/17.

Next time, read my posts more carefully....

[fatoni]

Originally Posted by rvoll

I see you're trying to be too cute by half... Again, the width of the wheel determines the LIMITS of the tires you can put on them as I said in my post. When you go beyond those limits, you either squeeze or stretch the tire. Those limits are set by the tire manufacturer to guarantee that the tire will not fail on a rim. If the tire does fail, and you have gone outside of those limits, you are liable for the tire failure, not the manufacturer. So for the Pilot Sport 4S, for example, you'll see the limits posted on the following chart:

https://www.michelinman.com/upload/m...t-sport-4s.pdf

So for a 215/45/17, the OEM spec, you can put it on a 7-8" rim. For a 225/45/17, you can put it on a 7-8.5" rim. But if I wanted to put on a 245/40/17, I could not put it on a 7.5" rim. The narrower the sidewall, the more limited your rim range will be. So on my 7.5" rim, I could go up to 235/45/17.

Next time, read my posts more carefully....

okay so this is where you prove to have been wrong earlier then. if you put that tire on an 8" rim, its faster. you have post after post telling me that going wider is bad because the tread width will be too much for such a light car and now youre contradicting yourself. all i ever said was wider wheels (than 7") are faster. you have said that lowering cars too much is bad, too much tire is bad, and a bunch of other things that have nothing to do with what im saying. your "evidence" is rarely related to your conclusion and your conclusion is rarely related to the truth.

you dont know what youre talking about.