brt3

Dear Abby,

I am looking at purchasing the following wheel/tire combo from TireRack:

19x8.5 AMG Double Spoke 2pc Bright Sil w/Mach Lip (FRONT)
19x9.5 AMG Double Spoke 2pc Bright Sil w/Mach Lip (REAR)
245/35ZR19 Continental ContiSportContact 2 Vmax Blackwall (FRONT)
275/30ZR19 Continental ContiSportContact 2 Vmax Blackwall (REAR)

I was thinking of the Contis because their load rating seems more appropriate to my E55 Wagon than the PS2s. Also, the Contis seem to be one of the few tires that can handle the occasional burst of very high speed
(planning on delimiting my car). Though this would be infrequent I like to have a large margin of safety reserve for those occasional blasts through Nevada...

I'm a little hesitant since the Conti Vmax is so new that there is no test data available. Also, the stock Contis are one of the most unloved tires on this forum (for some reason the Porsche forums seem less harsh in their judgement of these tires; maybe that's because of the different weights of the 911 vs. the E55). One other concern is ride harshness with the decreased aspect ratio. This is a "real-world" performance car for me that is driven almost daily, and I'd like to keep the ride quality as close to stock as is possible. I realize that going to 19s will probably compromise ride quality, and it sounds as though these tires have a stronger construction that may increase the stiffness of the sidewalls. Tire noise is also a concern since my car is driven quite a bit. I don't want to make an expensive mistake, as the package I'm looking at costs around $6,000.

Should I have my head examined?

Nuts in Novato

Jakpro1

I have informed my attorney to prepare a cease and desist letter just in case you continue on this path and move to purchase Conti Sport Contact 2's.

In all seriousness, please don't do that. Seriously, if you have your heart set on Conti's, be a guinea pig for us and try the VMax's. Road and Track has them speed rated up to 220. I just cannot tell you the difference from Conti's to my PS2's.

Here is the review on VMax.


Flat-out with Conti's Vmax

Continental's ContiSportContact 2 Vmax is capable of speeds up to 220 mph. This is a damn sight more than I could say of myself, but there's fascinating technology in what makes a tire suitable for such velocities.

The Vmax evolved from ContiSportContact 2, already proven in the high-performance tire segment. Key to its capabilities are dissipating heat and withstanding extreme centrifugal forces.

The Vmax's tread depth is reduced by about 15 percent, thus cutting heat generation by half. Its sipe pattern, minute slits in the compound, enhances the Vmax's tread suppleness and regains a bit of the service life traded away by the reduced depth. There are more tread grooves, also beneficial in dissipating heat, and more "negative tread," that is, open areas helping to cool the tire and enhancing its wet-weather performance.

As a tire spins at high speed, stationary waves can develop in its tread and sidewalls. These waves, in turn, can generate heat through deformation of the tire material. On the Vmax, such waves are dampened through reinforcement of tread and sidewalls.

Its tread contour has multiple radii, optimized to distribute centrifugal forces more uniformly. To ensure integrity of the tire/wheel interface even at extreme speeds, the Vmax bead is stronger, with 36 wires in its core rather than the customary 25. The tire's belt and cap materials also are stronger than those of lesser tires.

Not surprisingly, the four introductory Vmax sizes won't fit your econobox: 245/35ZR-19, 275/30ZR-19; 235/35ZR-19 and 315/25ZR-19.

Last, let's analyze what happens when one of these tires is traveling 220 mph. (It'll also provide a review of tire nomenclature.) A 315/25ZR-19 tire is on a wheel of 19-in. diameter. Its sidewall-to-sidewall width is 315 mm or 12.4 in.; its sidewall height is 25 percent of this width, 79 mm or 3.1 in. Thus, its overall diameter-wheel diameter plus two sidewalls-is 25.2 in. Last, this gives a rolling circumference of 79.2 in. or 6.6 ft.

Now, 220 mph is 323 ft./sec. (i.e., rather more than a football field each second). And thus, at 220 mph a Continental ContiSportContact 2 Vmax 315/25ZR-19 revolves at a rate of 48.9 times per second. That is, each tread element encounters the road every 0.02 second.

That's what I'd call running flat-out!

brt3

Sorry -- maybe I didn't make it clear, but the Vmax is the tire I'm considering...

vraa

Why would you have to have your head examined?

If you don't like the tires, just burn out.

brt3

Been working those stock Contis pretty hard since reaching break-in mileage...

vraa

Do what Rafal did.
200ft burn outs!
ON TOP OF TRACKING THE CAR!

Jakpro1

I say what the heck....give it a shot...you'd only be out bout a grand if they suck. Not like they are gonna be the worst tires on Earth too. Would be great to see if they are any better the original Conti's. I say go for it.

You can always go PS2's in the future.

Sorry I misunderstood.

Good luck.

Marcus Frost

Mr. Nuts in Novato, you have a PM

-m