Traction on 20's?

[Agarc]

you get some lightweight 20s and it wont be such and issue i had those stock big ol rims the camaro come with i think weight like 32-34 lbs and switch to some vossen cv3 i think 24-26 lbs you could feel it better.. i even thing forge star has some 20s that weight 20-22 lbs

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[minjitta]

SVT prototype has already been spotted with 295's up front and the S197 could swallow 315's up front with the right wheels and some negative camber and a shorter overall tire height (less than 26.7").

I'm just glad the 14" Brembo option will fit 18" wheels... I don't want 19" wheels or 20" wheels just based on the cost of the tires alone.

Also, the S197 could swallow some pretty wide tires out back too and since this car has a wider track and fenders to match, I would be shocked if you couldn't fit at least 315's out back without rubbing. Supposedly the SVT car is going to have 11" wide front wheels and 13" wide rear wheels... 295's up front and something substantially larger out back like 315's or 335's. For handling I would fight for a square tire setup though to help ward off understeer.

The problem is to find the wheels you like to accommodated 315 or 335 :frusty:
I like 18" in front and 19" outback

 

[qwkcoupe]

....
If you want peak performance in a corner, less sidewall works much better.
The more sidewall you have the more likely the contact patch will continue in its original direction as opposed to where your aiming it. Theres a tech term for this, but I dont know it

Sidewall, plus don't forget the height and/or stiffness of the tread blocks themselves, under high turning/lateral G force load negate toe and the amount of Ackermann designed into the suspension geometry. The the tires induce their own

Ackermann Effect

I like almost worn out tires, other than rain of course, because the tread blocks are short/stiff helping to maintain the desired toe/ackermann without having a bunch of toe/ackermann that would wear the tires out during normal commuting driving.

 

[Norm Peterson]

Aside from a slick, the amount of sidewall you can run really doesn't affect your traction.

I'm sure that all those Camaro 1LE owners (285/35-20) who are consistently having more difficulty launching without excessive wheelspin would take issue with that. The plain SS on 275/40-20's does better.

In real-world street driving, sidewall height doesn't matter. But at the dragstrip where you need all the help you can find, a more compliant sidewall will still take the shock loading at launch better. Particularly if you're running a stick shift.

Some of the best performing cars in the world are riding on 20's. If traction on 20's was an issue these cars wouldn't have them.

The main issue will 20 inch wheels and lower profile tires is decreased ride comfort.

Wheel diameters are also driven by brake rotor diameter (typically rotor diameter + 4") and by the stylists strictly for appearance reasons. It is assumed that the tire and suspension engineers will figure out a way to make them work without sacrificing too much performance - remember that we only have data for the "big wheel" end result. Not data from any possible testing along the development path with smaller diameters for comparison against data for the big wheel configuration at a similar stage of development.


Norm

 

[Build'em]

Some of the best performing cars in the world are riding on 20's. If traction on 20's was an issue these cars wouldn't have them.

The main issue will 20 inch wheels and lower profile tires is decreased ride comfort.

You are so clueless. Think before you post the cars you just listed are all wheel drive except the F12 Ferarri, which is not a rocket due to weight.
I've done testing of wheels and the affects of changing sizes from 15-20" inches. There is a huge difference in acceleration, braking and mpg. The taller the tire: longer braking distance, worse mpgs and slower acceleration. The only thing taller wheels might improve SLIGHTLY, is cornering, oh and eyecandy. Infact, we took a 2006 mustang GT with 16" wheels oem and did all the testing involving accel, braking, cornering, fuel, etc, etc. then we tested the numbers for EVERY 1" increase in wheel height. When we got to 19" whlz,the car was 1 full sec slower in all acceleratin categories, got 2.34mpg less mpg and took 2.8 feet more to stop. Skid pad went from .87g to .89, negligible really. Just remember, taller wheels are not better but worse, period. That's also why we need more and more hp to keep a car 8 yrs newer as fast as the 150lb lighter car from those 8 yrs ago. Tall wheels are eyecandy at best. There's to much science and fact behind the testing from many others as well to prove my point. Nuff said.

 

[Build'em]

Tire side wall height & corresponding suspension setup decides comfort, not wheel height.

 

[Build'em]

Norm Peterson is also correct. I must also point out all the people that go for that "wide tire" look. That look does not equal better grip/traction in a straight line. Wider will most aid in cornering and braking. I've done tons of testing on base 5.0 18x8" wheels. The 235/50 tire size is for better fuel/EPA ratings.the best tire width for the base 8" wide wheel is a 245/40 or 245/45. Of course tire type and compound help too. I went to a 245/40/18 tire on oem wheels bt went with the new pilot super sport that's on the new C7 vette. I tried a 235/245/255 with 45 & 40 series sidewalls. With est 480 crank hp, the 245/40 utilized the tire (the best) properly as the outer tread rib is for acceleration grip. You want kool looks with so, so grip and better cornering, go wider.

 

[Taneras]

When we got to 19" whlz,the car was 1 full sec slower in all acceleratin categories.

All categories?

So its 0-30/0-40/0-50/0-60/1/4 mile, everything was a second slower across the board? That doesn't sound right at all.

 

[5.0GT]

All categories?

So its 0-30/0-40/0-50/0-60/1/4 mile, everything was a second slower across the board? That doesn't sound right at all.

1 sec is total b.s lmao

 

[Norm Peterson]

All categories?

So its 0-30/0-40/0-50/0-60/1/4 mile, everything was a second slower across the board? That doesn't sound right at all.

If the extra second was because the 19's launched that much more poorly, a 1-second gap would follow every one of those zero-to-speeds and follow pretty close on ET.

1 sec is total b.s lmao

You have test data to back that statement up? Or inside knowledge that Build'em's test procedure was flawed? If you can bring some tech and not just more unsupported opinion I will listen.


Norm

 

[Taneras]

If the extra second was because the 19's launched that much more poorly, a 1-second gap would follow every one of those zero-to-speeds and follow pretty close on ET.

No it wouldn't.

The larger the rim the more rotational mass you have. If you lost a full second due to the launch, you'd continue to lose more time as you continued to accelerate. Losing a second at launch would translate into a lot more than a second at the end of, say, a quarter mile run.

You have test data to back that statement up? Or inside knowledge that Build'em's test procedure was flawed? If you can bring some tech and not just more unsupported opinion I will listen.


Norm

What silly questions. Build'em hasn't presented any data to back up his statements nor has he explained his test procedure. Perhaps you should be asking him to bring some "tech" to back up his claims.

 

[Grimace427]

You have test data to back that statement up? Or inside knowledge that Build'em's test procedure was flawed? If you can bring some tech and not just more unsupported opinion I will listen.


Norm

Same goes for the other side of the argument, Norm. How was this 'test' conducted and how many variables did they remove?


I've only seen one of these tests done on a street car through all performance metrics(accel, braking, turning) and the differences were negligible. Also, braking performance was improved with the larger and heavier wheels contrary to popular belief. The problem with that test(Car & Driver IIRC) was that the different sized wheels carried different widths and importantly models of tire so all of the data should have been thrown out.

 

[Norm Peterson]

No it wouldn't.

The larger the rim the more rotational mass you have. If you lost a full second due to the launch, you'd continue to lose more time as you continued to accelerate. Losing a second at launch would translate into a lot more than a second at the end of, say, a quarter mile run.

Rotational inertia is a lot smaller of a factor than people try to give it credit for. I've run the mass moment of inertia numbers and what accelerating them rotationally "steals" from forward acceleration enough times, so unless there was a huge difference in weight between the 16's and the 19's we're talking about a small fraction of a second for this effect, maybe around a tenth of a second.


Sure, it'd be nice if Build'em had provided a little more information, but what he has posted is still more useful than somebody with mostly appearance posts to his credit calling it bs without giving a reason.


Grimace - I'm not surprised. Heavier wheels (more rotational inertia) should be just a little less likely to lock up immediately (activating ABS brake release) due to variability of contact patch loading on a millisecond time level. Sam Strano claims to be able to notice a similar difference on acceleration where lighter drive wheels make the car a little "touchier" to drive off the corners than with heavier ones.


Norm

 

[Grimace427]

Sam Strano claims to be able to notice a similar difference on acceleration where lighter drive wheels make the car a little "touchier" to drive off the corners than with heavier ones.


Norm

Likely a gyroscopic effect.

 

[Taneras]

Rotational inertia is a lot smaller of a factor than people try to give it credit for. I've run the mass moment of inertia numbers and what accelerating them rotationally "steals" from forward acceleration enough times, so unless there was a huge difference in weight between the 16's and the 19's we're talking about a small fraction of a second for this effect, maybe around a tenth of a second.

Considering Build'em went to the hundredths of a mile when telling us the mpg changes by going from 16's-19's (he said it decreased mpg by 2.34), I think a tenth of a second is noteworthy on a quarter mile run.

Sure, it'd be nice if Build'em had provided a little more information, but what he has posted is still more useful than somebody with mostly appearance posts to his credit calling it bs without giving a reason.

What can be asserted without evidence can be dismissed without evidence. Build'em didn't post a shred of evidence to back up his claims, why should anyone lift a finger to try and disprove said claims?

Even being charitable, not instantly dismissing his claims as bogus, and actually giving him the benefit of the doubt doesn't do him any good. From the get go, you cannot even fit the 16 inch V6 oem rims on the GT to even do the testing in the first place. A few V6 guys out there that tried to add on some GT take off brakes to their cars found out that the base 16 inch rims weren't giving enough clearance. You needed the 17 inch pony pack wheels (or aftermarkets) to be able to throw on the GT brakes.

But lets assume that they changed the brakes to give them clearance to fit the 16 inch oem rims on the GT, Build'em is claiming a full second lost "all acceleration categories" between 16 and 19 inch wheels. I'm going to assume that the 0-60 and 1/4 mile times are included in the aforementioned acceleration categories seeing as they're probably the most common measurements for car acceleration.

Car and Driver did a first drive test on the 2005 Mustang GT Premium and pulled a 5.2 0-60 and a 13.8 1/4 mile run. The Premium GT came with 18 inch rims. Dropping that down to the 16's Build'em mentioned nets you 2 inches, which is one inch short of what he was talking about (16-19 inch wheels). That's 2/3rds, 2/3rds of a second is .66 seconds.

Just using rough figures, he's suggesting that taking a 2006 Mustang GT Premium and removing its 18 inch rims and placing 16 inch OEM rims in their place will drop the GT's 0-60 from 5.2 to 4.54 seconds, and its 1/4 mile time from 13.8 to 13.14.

Now, do I really need to explain further why a 300hp 3500lb car won't be doing a 4.5 0-60 and a 13.1 1/4 mile? Or explain why a 2005-2010 GT won't be reaching the same benchmarks in acceleration that a 2011+ GT is simply by "upgrading" their 18 inch wheels to the 16 OEM V6 wheels? That's absurd at a common sense level. I don't need to pull out a ruler to verify that my size 12 shoes aren't 7 inches long. Just eye'ing it is enough. Likewise, I didn't really need to look up all these numbers and compare them in order to call bs on what Build'em said. You aren't going to lose a full second in any meaningful measure of acceleration by just changing your wheel size 3 inches.

EDIT: Did Build'em just troll me? :lol:

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