Another curious question

[Removed user as requested]

I have been told that the ideal wheel size for a handling car is 17" on all 4.

Tests have been made on same car and same driver with smaller than 17 and larger (like 18-19).

Though you can fit 14" brakes on an 18" rim vs a 13" brake on a 17 the tests showed that the car with the fastest circuit times was with 17" wheels.

This means anything smaller or larger than 17 = compromise.

My question now is...

If that be true (i checked a lamborghini diablo they use 17s on all 4 also) why on earth every single pro-touring car I ever seen or read about runs 18 on the rear and 17 on the front or 19 rear 18 front or 18 all 4 but never 17 all 4?

Am I missing something here?

I know you can run 335x17Z on the rear... why does everyone go larger than 17 when 17 = Ideal?

Is it because you cant get 17x13 wide wheels to make the 335s the ideal fit but they can be gotten in 18" size? Or what?

George

[srh3trinity]

It is probably a compromise between looks and function along with the need for bigger wheels to clear larger brakes. I think Bad Penny was wearing all 17 inch Forgelines at one point in time, but they were changed in favor of 18 inch wheels for brake clearance. Mary Pozzi was running 17's on her Camaro before the teardown too.

[Removed user as requested]

So why would you want bigger brakes when 17's still go better than 18s with the larger brakes? Is that more so looks/street stopping more so than the slight increase performance of the 17?

[MonzaRacer]

Balance. Available tires for said application. And what "fits" over what just fits.
While you can "just run 17s" because they are the best, its not always true, a taller tire in a 335 will have a bigger footprint over a shorter one. Also if you run 13 in brakes to the ragged edge in testing and such, then you upset it by adding 14in, then needing to clear them becomes a problem.
now look at C6 Corvettes, 18 front/19rear, yet both are same diameter, BUT the last article Isaw in older magazine was when the yellow C6 was tested and the writer loved its balance and grip.
Used to be the best tire for the job was 15, then a 16, now 17s.
Remember technology follows trends and the new trend is 17.
13/14 =stock, 15=performance.
Then 14/15=stock,16=performance.
Now 15/16=stock, 17=performance.
Give tire and car technology a few years and the trend will advance, or we will be in to spherical "wheels" like in I,Robot.
The given tire technology right now, number of available widths and diameters AND compounds are running in the 17 in range but leaking over to 18s and 19s.
The technology was in SBC 1st gen, then SBC 2nd gen, then Gen 3. and now we are up to what Gen 5? and each subsequent generation of engine, tire,ABS,trans gets better.
Remember when Saginaws were top dog manual,,,then came T10 and Muncie, then came Super T10, then Richmonds and T4s, then T5ods, then T56, and Tremec, and ZF.
See a trend. A Model T was the height of mechanical creation and all its addons/mods. ever see one with tractor conversion? Think of it as the first ultimate hot rod!
Well you get picture.
Right now you go get any set of performance tire brochures from a Bridgestone/Firestone dealer, look at number of 16/17 performance tires, 16s are waning, 17s are flush in models and sizes, eh 18s so so as the OEMs step up to better compounds/designs.
Cant wait to see what comes up for fitting behind a 26"? Not me!

[wmhjr]

Right now you go get any set of performance tire brochures from a Bridgestone/Firestone dealer, look at number of 16/17 performance tires, 16s are waning, 17s are flush in models and sizes, eh 18s so so as the OEMs step up to better compounds/designs.
Cant wait to see what comes up for fitting behind a 26"? Not me!

Lee, I don't really agree with your thoughts here. I think it's kind of like about 10 yrs ago when one of our (elderly and frankly incompetent) school board members made the statement during a public board meeting that we should make Latin a mandatory part of our curriculum because statisticly kids who took latin did better on SATs. His conclusion was that taking latin resulted in better SAT scores. The truth is that kids who had taken latin as electives were the more studious and serious students and would obviously have tested better regardless of the latin.

Here, I think you're sort of concluding that because so many more "larger" tire sizes are common that they are better - or at least as good - performers. Not necessarily. No more than heavier cars are better performers (as cars have ALSO gotten heavier). The reason that larger tires are sold is because they're being put on OEM cars, and the reason they're on OEM cars is for styling. Look at the new camaro. One of the easiest ways to improve the performance of the new model is to replace the wagon wheels with smaller, better engineered, wheels. But for normal driving and reasonable performance (which is how 99.99% of cars are driven) 18s will perform as well as 17s with low profile tires.

How many F1 cars run 18" or 20" wheels? None. So, for this and many other reasons I think the answer to the OPs question is...

A compromise between looks and performance. For performance, 17s are better.

[wmhjr]

Oh, crap - I just realized I wrote something that may come across wrong. Lee, the school board member was incompetent for LOTS of reasons. I disagree with your conclusions about larger wheels/tires but absolutely and certainly do NOT lump you in the same category!

[Removed user as requested]

I understand corvettes etc use 19 in the rear but a lamborghini is a much higher handling car than a corvette and it runs 17's on all 4.

To say the trend is changing and hence 18s are becoming better doesnt really work because if a 17" wheel out handles the identical car with an 18" wheel setup, even if 100 years go by 17" wheel will still outhandle 18" wheel.

So really I was just wondering why people use 18 rear 17 front or 19 rear 18 front... why dont people just run the same size on all 4? Doesnt that make the car more balanced by having the same sized rim on all 4?

It seems to me its more about how the car looks rather than the slight increase in performance of a 17". People like the look of 18-19 so they put that on. But if a car is purposelly built ot handle at its maximum, then 17's would be used even if the 18s looked better.

Do I atleast have something right here?

[alowerlevel]

Where did you find these tests at? Id like to see them.


BTW, theres not a Lambo currently made with 17" wheels, they all have 18's or 19's on them now.

[Drewcrane]

Where did you find these tests at? Id like to see them.


BTW, theres not a Lambo currently made with 17" wheels, they all have 18's or 19's on them now.


Yes you must post these tests for a better discussion:spank2:

[DLinson]

Are 18" wheels a compromise? Kyle and Bryan are running 18" front and back on their Camaros and the they took 1st and 2nd in the autocross ate RTTH6. Driver skill has a lot to do with that too but they are both great handling cars with 18" wheels. The suspension was designed to work with those wheels.

If you keep the same OD tire but move from a 17" to an 18" you loose sidewall compliance which may hurt. If you keep the same sidewall height and go to a 1" larger OD tire then you won't affect that. The added unsprung weight will be an issue but thats where shock and spring tuning come in.

It's also getting harder to finde 17" tires. BFG cut back on their 17" offerings and are stepping up to 18" and larger for the wider tires. The tire manufactures also follow the automanufactures for tires sizes.

A guy at my work owned a Mini Cooper and was in a Mini club. Their concensus was that the Mini's with 15 inch wheels with more tire sidewall compliance handled better than the 17" wheels and tires.

I run 17" wheels on my Nova but back when I got the wheels, 17" wheels were considered big.

Dennis

[cheapthrillz]

Where did you find these tests at? Id like to see them.


BTW, theres not a Lambo currently made with 17" wheels, they all have 18's or 19's on them now.

Agreed. You can't make a statement like "Tests have been made on same car and same driver with smaller than 17 and larger blah blah blah........." without producing any type of numbers and facts and expect to be taken seriously.

Please read this thread: https://www.pro-touring.com/forum/showthread.php?t=51511

Hopefully this will give you a little more insight.

[Type73LT]

I must really be out of it. I use 14 245 front and 15 275 rear. They are within a 1/4 of being the same diameter.

Yes I may lose some performance on a track. How much do I get to a track. On the street most people can not drive so I can make them look silly easy enough on the ramps and twisties.

In an autocross I hang with the 350 Z's. I think that is not bad for a 37 year old car with minor suspension mods.

[Steve1968LS2]

I wouldn't be surprised if 17s were better than 18s..

When I won the Optima it was on 17s and the main benefit was that we could run a taller profile tire (which gives a better feel)

When I went to a dropped front upright I lost the ability to run 17s so I went bigger on the brakes.

However, the difference between the two is minimal, but there is one.

I think people go 18 for several reasons. One is looks, one is more tires available and the last one is you can run giant brakes.

[406 Q-ship]

I believe there will be an eternal decussion on rim sizes, well at least for the forseeable future.

I run 17" for all the reasons that have been given in other decussions (moment of interia and weight). I may end up going to 18's at some point because of tire sizes going away. I am not happy about it, how long before 18" tires become "obsolete" and I have to buy rims once again, horrid part is that the 17's I started with are the best choice when looking at performance. With the up in rim size, my brakes and driveline will have to work harder to achieve the same performance.

Most builders and owners choose rims based on appearance, which is fine (I did too.....to a point).



....To say the trend is changing and hence 18s are becoming better doesnt really work because if a 17" wheel out handles the identical car with an 18" wheel setup, even if 100 years go by 17" wheel will still outhandle 18" wheel.


That is a blanket statement that is way to broad. If technology advanced for both 17 and 18 tires at the same pace, then yes the 17 will keep that advantage. In the real world it is about consumer demand and with that the tech is being used on 18" (and up sizes), while 17" and down get neglicited like a red-headed step child. Advantage to the 18's.....for now.

Soon we may be forced into 20's and then the fight will be between 20's and 22's......good God! I will be out searching the backlots for 17 or 18 tires to keep my car on the street.

Bigger ISN'T always better!

[compos mentis]

What about the ride quality of 17's vs. 18's?

[wmhjr]

In the real world it is about consumer demand and with that the tech is being used on 18" (and up sizes), while 17" and down get neglicited like a red-headed step child. Advantage to the 18's.....for now.

That's exactly right. Except I'd define "advantage" as more available tires. Not better performance. The reason there are so many more 18" tire options than 17" is because people are buying them - NOT because they are better. People are buying them for looks. Same reason the idjuts are buying 22" wheels - though IMHO those looks are horrendous and should be illegal as they are an disgrace to human decency. I'm somewhat guilty myself. I'm running 18" wheels, when I know for pure performance I'd be better off with 17". But I'd also be better off with a cage to stiffen the vert chassis, but that's just another compromise I made for "style" vs "substance". F1 does not run large wheels. Matter of fact, F1 USED to run SMALLER wheels until they were prevented from doing so. Remember the Tyrrell P34? Of course, they used the combination advantage of 4 front wheels with smaller diameter wheels to their advantage for that one.

There is certainly an argument to be made about just how much different combinations give you. However, there is no substance whatsoever to the idea that because so many more tire sizes are available in larger diameters, larger diameters must be higher performance. We I building a purely track car, I'd probably be running 17".

You could focus all the R&D money in the world and you'd never ever ever make 36" wheels outhandle 17" wheels in a 3000lb car. I question whether you could with sizes much closer to 17" as well. Physics is Physics. At least until we perfect the flux capacitor.

[406 Q-ship]

That's exactly right. Except I'd define "advantage" as more available tires. Not better performance. The reason there are so many more 18" tire options than 17" is because people are buying them - NOT because they are better. People are buying them for looks.

I am saying along with more sizes is that any new technology design (tread pattern, belt materials, or the belt weave pattern)will be applied to the bigger rim tires due to consumer demand, while the smaller rim sized tires will get left using the older tech. The larger rims will begin to put down better times, not because of there being superior but due to negliect to the smaller rim tires. Some of the lastest model of tires do not even come in 17" sizes. I would say to the tire companies that not everyone wants those big a** ugly wagon wheels, please make the common sizes for those of us who aren't following the latest trend.

I know that some go for rims for pure looks and that is great but that doesn't mean the rest of us should have to suffer because we didn't. I don't mind 18" but beyond that it is just rediculous.

[DarkBuddha]

I'm sure it's been said, but it's not as simple as one size wheel being the best choice in all cases. There are far too many factors that contribute to making wheel choice. There are tons of considerations like clearing brakes, fitting the wheel wells, tire selection, tire width, sidewall height, rotating mass, unsprung weight, durability, etc. Personally, after my own personal experience and research and talking with lots of racers, I'd be more concerned about unsprung weight and rotating mass than anything else.

[a73formula]

QUOTE: If you keep the same OD tire but move from a 17" to an 18" you loose sidewall compliance which may hurt. If you keep the same sidewall height and go to a 1" larger OD tire then you won't affect that.


I have to agree with dlinson, its more the amount of sidewall that makes the bigger difference than the rim size. I also have to argue with the statement that the lamborgini's are out handling the corvettes, from what I've seen racing the corvettes are even if not ahead. Just my opinion though.

[ArtosDracon]

If you're refering to that article where they worked from liek 15s to 19s on a stock Golf then also keep in mind that they did not use the same tires for all the tests and they did minimal handling tests, crap article IMHO.

[Removed user as requested]

So for a person who has 14" wheels with stock Drum brakes on the rear and 2 front discs on the front (original 68 Charger)... who does not mind mini tubbing the rear and sticking 335 and even 345 if available on the rear to get some serious traction and would buy the brakes that fit the wheels... in my case am I then since looking for best performance be looking at 17s on all 4?

In fact, what 17s offer 335/345 wide which have a good sidewall (not too small but not too big) with light rotational mass and unsprung weight (whatever that is... i just read here its important :nopity:)

[ArtosDracon]

Unsprung weight is just weight that is on the suspension itself, and is not supported by the spings of the vehicle, unsprung. You essentially covered it with rotational mass.

Hoosier and Kuhmo both make 335/35-17, including the Exsta XS which I think Mary said she's used before with decent results. The hoosiers and top notch though they don't even have a wear rating, lol.

[Removed user as requested]

Here are some of the tests done.

http://www.caranddriver.com/features/10q1/effects_of_upsized_wheels_and_tires_tested-tech_dept

http://www.motortrend.com/features/112_0405_big_wheels/acceleration.html

http://www.caranddriver.com/reviews/comparisons/05q4/tire_test_the_quick_and_the_tread-comparison_tests

http://www.caranddriver.com/reviews/comparisons/09q2/tire_test_nine_affordable_summer_tires_take_on_the _michelin_ps2-comparison_tests

[a73formula]

the first article shows that the 18" set up was the best, I'm confused why you are so sold on your 17" theory. I think most people here have been saying 18".

[ArtosDracon]

I was afraid that was the article you were referring to, completely useless article in my opinion. They do all of one handling test, and they used a soft, everyday car and they don't even use the same tire compound through all the tests. Not what I would call a good benchmark, unless you're just looking at wheels for your soft, heavy, modern car.

[DarkBuddha]

Unsprung weight is just weight that is on the suspension itself, and is not supported by the spings of the vehicle, unsprung. You essentially covered it with rotational mass.

Just to be clear, functionally, unsprung weight and rotational mass are two different things, though in this case, they are clearly directly related.

[ArtosDracon]

Just to be clear, functionally, unsprung weight and rotational mass are two different things, though in this case, they are clearly directly related.

Touche, I did not mean to imply that they were in any way the same, just directly correlated within the context of his post. Good catch.

[JEFFTATE]

There are better tire choices in the 18" size and the ability to use bigger brakes ..