Louie83

iTrader: (3)

18's and 19s?

LS69TA

iTrader: (30)

They don't use extremely heavy wheels, like alot of the aftermarket 18 and 19 inch wheels are. They also have enough HP to make up for any extra weight.

98a4z28-410rwhp

because a 500 hp viper will never stop spinning without a bunch of meat

Danny2tek

iTrader: (1)

cuz they have more then enough power to make them spin

Phoenix 5.7

iTrader: (7)

this is just my opinion, but one idea i had is that the taller size allows the car to go faster at lower RPMs without having a tall sidewall(tall sidewall is usually bad for handling). they have the HP to overcome the extra hp it takes to turn the bigger wheels

Xsta Z 28

iTrader: (2)

Because the Vette and Viper are not designed to go only in a straight line . .

Your use of the word "Performance" is too generic.

Plus not all big wheels hurt performance . . .

Deep Blue

What he said. As someone on the Vette forum observed, we sometimes seem to obsess over 1/4 mile times. Don't get me wrong, sheer acceleration is an important part of performance, but on a road course, you drag race between corners.

The Alchemist

iTrader: (19)

Plus you need the extra large diameter wheel to fit 13" 14" rotors as found on the vette and viper.

Deep Blue

Alchemist and Phoenix 57 also make good points.

I don't think this is a reason but if one runs bigger wheels and lower profile tires, there will be less of a descent on that corner in the event of a flat or blow out;may be a bit easier to maintain control or limp to a service station if you have to.

Nine Ball

iTrader: (38)

18s are as big as you need for handling performance, and that would only be if you had larger brake rotors that required the clearance. Most road-racers and autocross guys prefer 16-17" wheels.

Vettes and Vipers come with 19s on the rear mostly for bling factor. They know that 95% of Viper and Vette owners never push the limits of those cars anyways.

Deep Blue

But then why did Ferrari stick with 19s on its track oriented F430 Challenge and FXX?

Phoenix 5.7

iTrader: (7)

brake size. those cars have humongus brakes that won't fit in any other size rim

Cop Car

iTrader: (14)

you should stay with a wheel that is as small a diameter as possible. ONLY reason why you should get bigger wheels is to accomidate bigger brakes IMO

the Z06 needs those huge wheels in the front to let those big brakes be there. the rears probably could be in an inch smaller but GM knows what they are doing

Deep Blue

Good discussion here guys; now I'm not trying to flame, just trying to understand the underlying principle.

Why does one want a wheel diameter as small as possible? I mean you need big brakes to be competitive these days (unless the vehicle weighs practically nothing) and a small wheel also typically means the tire sidewall would have to be super stiff for predictable handling. Someone related this discussion to Formula 1 a while back since they have relatively small wheels and tires with large sidewalls but I can't remember the reason. Then again the Carrera GT uses twenties on the rear.

LTSpeed

The bigger brakes are a huge reason to go 17+. Mine stops way shorter than any stock LT1/LS1 ('vette or f-body). Larger wheels can provide lower rolling resistance and a longer contact patch (front to rear), but when the overall diameter stays near the 25.7" stock size, as is usually the case, there's really no difference.

In fact, since all 17+ wheels/tires weigh more than their smaller cousins, the increase in unsprung mass can hamper road handling unless there are major suspension mods to compensate. Under normal street conditions, though, most LT1/LS1 drivers never notice the difference. On Autocross or Road Courses, it's a real setback.

spy2520

iTrader: (3)

could one reason be that the vettes are somewhat light?

Viper

iTrader: (6)

"On Autocross or Road Courses, it's a real setback."

How? When I went to 17's over 16's my autox times got better.

madmo

iTrader: (2)

Who said larger dia wheels are a bad thing? Larger wheels provide more speed and handling but not that great 60' times must guys on this site are looking for, for instance if you had a 16'' rim vs 18'' you will gain some mph in the traps, but you have to understand that those 18'' might have less bite than the taller sidewall tires of the 16''. Just got to pick your poison.

LTSpeed

Are you familiar with the concept of unsprung mass?

You did not pick up time by just switching to 17's. If all else is equal, (width, compounds, etc...) you would definitely slow down--your car is heavier. It's likely you changed much more than just diameter.

With the right 16's, you can run some pretty decent AutoX times--right up until your stock brakes fade away. 17x11's are about the best you can do with an f-body for AutoX. 18x11's or bigger are too massive.

Deep Blue

"Are you familiar with the concept of unsprung mass?

You did not pick up time by just switching to 17's. If all else is equal, (width, compounds, etc...) you would definitely slow down--your car is heavier. It's likely you changed much more than just diameter."


This is an oversimplification where AutoX is concerned because it doesn't account for the increased grip and quicker response that can come with the ability to run lower aspect ratio tires. And if you are willing to pay enough, you can find lightweight 17 and 18 inch wheels that weigh the same or less than our stock 16s. The larger tires would of course add weight but one could at least try to choose the lightest tire possible.