Pro-Touring defined?

[ProStreet R/T]

Thats a pretty closed minded statement, (no disrespect intended)
The Porsche Carrera GT runs 20's in the rear,the C6 Z06 runs 19's as does the Viper GTS. To say they are not perfomers is a blind assumption. I think it has alot to do with cavman no like fire. Only because he doesn't understand.

I agree, and honestly everyone likes a little bling. If it were 100% about performance we would all run 15's, afterall the fastest cars in the world (F1) run small wheels, as do nextel cup cars, Indy, and so on.

[Ralph LoGrasso]

I agree, and honestly everyone likes a little bling. If it were 100% about performance we would all run 15's, afterall the fastest cars in the world (F1) run small wheels, as do nextel cup cars, Indy, and so on.

Not to argue with ya, as I understand the point you were trying to make, but I thought I read somewhere that F1 cars run such small wheels because the tire actually acts as most of the spring for the suspension, due to the configiraton? Or something along those lines.

Most GT style cars (C5R / C6R, GTS-R, all the porsche's) run 18s. I think lightweight 18" wheels / tires are the best balance of performance and asthetics, and possibly offer the greatest selection of race rubber.

[MrQuick]

don't get me wrong, I don't care for the big big(18+) rim, but on certain cars it is necassary= big brakes. must admit looks good, on some.
I still love the 15's on certain cars, GTO's and Chevelles... really dig the street machine look I grew up admiring. Look at my old 68 GTO, fatty tires on deep 15's and a serious demon drop any Joe dirt would love.

[sinned]

Thats a pretty closed minded statement, (no disrespect intended)
The Porsche Carrera GT runs 20's in the rear,the C6 Z06 runs 19's as does the Viper GTS. To say they are not perfomers is a blind assumption. I think it has alot to do with cavman no like fire. Only because he doesn't understand. ; )

Amen brother!

Actually Porsche and Corvette designers have admitted to adding bling (cross drilled rotors and oversize wheels) simply for the asthetic values-no performance advantage at all. Besides, when you can run 10's, pull over 1G and brake from 60MPH in under 120' than you are allowed a little bling I guess to sell more cars.

[MrQuick]

I'll give you that...hey you going to Vegas THIS YEAR????

[Ralph LoGrasso]

Actually Porsche and Corvette designers have admitted to adding bling (cross drilled rotors and oversize wheels) simply for the asthetic values-no performance advantage at all. Besides, when you can run 10's, pull over 1G and brake from 60MPH in under 120' than you are allowed a little bling I guess to sell more cars.

It’s obvious the argument of large diameter wheels being used on high performance cars is a bilateral one.

One side is the fact that they (19”+ wheels) can indeed perform to the standards we're looking for-- 1G handling and sub 120ft stopping distances, given the proper suspension setup. This realization of performance is something the guys using larger diameter wheels and tires can argue. "The '06 Z06 can do it with 19s and 345s, and so can my car."

However, the other side of the argument is that those performance figures are gained as a result of the culmination of countless hours of testing and tuning, by GM engineers, and unheard of amounts of money being used to fund said practices. This being done in order to optimize the suspension to function in accordance with their goals for the car, given the allotted wheel and tire sizes. This use of capital, parts exchange, and engineering analysis is something the average car guy just doesn't have at his disposal. Thus, if you're looking for exceptional performance right out of the box with limited tuning, you may want to look for a set of 18s, rather than 20s.

To recap, can large diameter wheels and tires be made to handle to exceptional standards? Sure. Is this something easily achieved by the average hot rodder? Definitely not; and we always have to keep in mind that while those 20s may perform admirably, all else equal, a set of 18s will perform better.

With that being said, as the old adage goes, “Run whatcha brung, and hope you brought enough” If 19s and 20s are what you like, then by all means, run them.

[Nine Ball]

If the goal with pro-touring cars is to have them perform, accelerate, brake, and handle as well as late model performance cars, then I don't see a problem if a car can do those things on a set of 20" wheels. Sure, it could run quicker on slicks, and handle better on road race tires/wheels. But, if it can still perform as good as or better than a late model sports car on its "Twaintees", then I'd say it is still pro-touring.

That also goes for having big booming systems, DVD players, power everything, A/C, etc... if a car has all that stuff and still can perform up to par, then that is good enough for me.

ps: if your car has drum brakes on it still, its NOT pro-touring!

[ProStreet R/T]

Not to argue with ya, as I understand the point you were trying to make, but I thought I read somewhere that F1 cars run such small wheels because the tire actually acts as most of the spring for the suspension, due to the configiraton? Or something along those lines.

Your thinking along the right lines, the tire plays a HUGE part in keeping the car planted on the track and the benefit is well worth the slight bit of sidewall flex they get. That and it's not really a fair comparison to even bring F1 tech into this argument, just was a point.

I agree 17-18" is the most ideal size for tire performance, brake capacity, and inertia.

Dennis- None of those cars run 10's and boy they better stop well short of 120ft from 60, viper is high 90's on a clean surface

Oh yeah, and drink more beer.

[parsonsj]

I agree, and honestly everyone likes a little bling.

Agreed. So when somebody challenges your 20" wheels as bling, say "yup, I like 'em".

Katz wanted me to run 17" wheels, and was annoyed with me and Kinesis for going to 18s. But, I like 'em.

jp

[andrewb70]

Thats a pretty closed minded statement, (no disrespect intended)
The Porsche Carrera GT runs 20's in the rear,the C6 Z06 runs 19's as does the Viper GTS. To say they are not perfomers is a blind assumption. I think it has alot to do with cavman no like fire. Only because he doesn't understand. ; )

Amen brother!

In all fairness wheel diameter is not really the issue. The issue is unsprung weight. You are right, the Porsche Carrera GT has 20 inch wheels in the rear, but let's look at the whole picture. The Carrera GT uses forged aluminum control arms and a push rod style suspension to cut unsprung weight. In addition the brake rotors are made of carbon fiber to cut unsprung weight even further. Last but not least, the wheels are made of forged magnesium, to further, SAY IT WITH ME NOW>>>REDUCE UNSPRUNG WEIGHT!

So to comparing a Carrera GT with 20 inch wheels to a Camaro with 20 inch wheels is not exactly fair.

Andrew

[Nine Ball]

....but, what if a Camaro with 20" wheels could perform just as good as the Porsche with its 20" wheels?

I think performance should be the goal, but once you achieve those goals then you can pretty much do whatever you wish on the car. Not really a "be all you can be" maxed out performance machine, just a vehicle that performs at a certain expectation level before bling and creature comforts are added in.

[parsonsj]

Unsprung weight, and moment of inertia. Moment of inertia is related to the square of the radius. There is a big difference between a 17" wheel and a 20" wheel even if the weight is the same. 8.5 (squared) is about 73. 10 (squared) is 100. So the moment of inertia is nearly 30% higher in the 20" wheel if everything else is equal.

jp

[andrewb70]

If, hypothetically speaking a Camaro with 20" wheels performs the same as a Porsche Carrera, then by all means keep the 20s. The point is that a Camaro with 20" will never, ever get even close to that performance level, ESPECIALLY with 20" wheels.

Andrew

....but, what if a Camaro with 20" wheels could perform just as good as the Porsche with its 20" wheels?

I think performance should be the goal, but once you achieve those goals then you can pretty much do whatever you wish on the car. Not really a "be all you can be" maxed out performance machine, just a vehicle that performs at a certain expectation level before bling and creature comforts are added in.

[ProStreet R/T]

Curious, am I the only one with a separate set of track wheels? Honestly I don't push my vehicles hard enough on the street where 18's vs 20's or even 22's will make any bit of difference. On a very rare occasion I get on it a little but in CA your just asking for trouble. So I drive it everyday with the 20's and change wheels when it's play time. Best of both worlds


Or just man up and build something awd with a TT small block. You will waste just about anything on street tires with those clunky 20's

[sinned]

OK, how about this. Anyone care to lay money down on which would be faster around the track....a new Porsche as delivered with the best 20" tires available or the same exact car with 18's and the best 18" tires available. Now tell me why it has 20's...sure it is for performance.

[TonyL]

interesting.

so Joes camaro, if it had dubs, even if they weighed the same as if it had 17s, would suffer a performance loss? would this loss be clearly measurable in performance data?
IE 60 foot times or lap times at the AutoX? how much would you think?

Unexpected/constructive tangent.

[sinned]

I'll give you that...hey you going to Vegas THIS YEAR????

You want to spot me airfare and hotel accomodations? Yeah, I didn't figure.


No really it's my anniversary week, we were almost going to make a dual trip out of it but it's the big 10 year mark so I think down south like Laguna Beach or something.

[TonyL]

you see? THIS is the kind of article we need to see in PHR. Actual comparative tests. Side by side. I'd love to see guys from here put their cars up against new cars.
Sport compact or one of those mags has an Ultimate streetcar shootout. tested the hell outta the cars, and the best one, (an S2000) could barley keep up with a corvette by the numbers.

[sinned]

interesting.

so Joes camaro, if it had dubs, even if they weighed the same as if it had 17s, would suffer a performance loss? would this loss be clearly measurable in performance data?
IE 60 foot times or lap times at the AutoX? how much would you think?

Unexpected/constructive tangent.

Yes, yes and no idea. The loss would be measurable to Joe as he had to adjust his driving to compensate for slower turn in, earlier braking and slower acceleration off corner. That would determine how much slower he ran.

[ProStreet R/T]

interesting.

so Joes camaro, if it had dubs, even if they weighed the same as if it had 17s, would suffer a performance loss? would this loss be clearly measurable in performance data?
IE 60 foot times or lap times at the AutoX? how much would you think?

Unexpected/constructive tangent.

Yes it would suffer a noticible loss in performance in all areas. And chances are the larger wheels carry more weight farther out on the radius which compounds the issue.

For example: Going from a stock style cast 15" wheel with slick that weighs roughly 50lbs per wheel.. to a race wheel (bogart etc.) that with the same tire weighs in at 35lbs each. Changing just the rear wheels resulted in a .10 sec drop in et on a mid 13sec truck. Go to light weight 15x4 fronts and you can easily drop another .10-.15 Thats just droping 30lbs of rotational mass with the same radius. Now compare a set of nice 18's with tires, probably weighing in the 55lb range, with a set of 20's that can eaily weight 70+ with tires and there is a dramatic change. Believe me going from 15" light weight race wheels to 20x10's with 295mm tires you can feel it big time.