OEM & Track Wheel Alternatives ~ 18" & 19"

[MichaelP]

Just a performance wheel update claim. From a Dymag distributor site: ".... Carbon Magnesium Car Wheel - Summary The performance gain achieved by reducing the wheel mass (Un-sprung Mass) can be quantified using a factor of six. This means that to achieve the same performance gain by reducing the body mass, it is necessary to remove six times the wheel weight saving.

Example: A saving of 2Kg Per Wheel x 4 Wheels = Removing 48 Kg from the Bodywork.

In some instances, Dymag's Carbon Mag wheels have reduced the wheel weight by up to 5Kg per wheel, which equates to saving 120Kg from the bodywork to get the same performance advantage. ...." see, http://www.rotaryart.uk.com/acatalog...Wheels_18.html

Hum, a potential 264 lbs, that's not insignificant. Still awfully costly however.

Cheers

[marshallwales]

Hi All,
I've had my R8 now for a few months and have done 3 track days using the stock 19" P Zero's.
I'm now trying to select a dedicated track tire which I'll switch out for track days.

I noticed some in this post are using the Toyo R888.
The load rating for the rear matches Audi spec but the load rating for the fronts is 87 rather than 91. Should I be concerned about this? (235/35ZR19 87Y).

I'm also considering using 18" Michelin Pilot Sport Cups, but again having problems matching load ratings. The 18" rears (285/30ZR18) are rated at 93Y instead of 100Y.
I'm considering the 18" rather than 19" Sport Cups because I was told the 19's use a different tread compound that isn't as good as the 18s.

All help is appreciated.

[Bodhii]

Audi R8's curb weight is 3439 lb (1560 kg)

The load index (87) is the tire size's assigned numerical value used to compare relative load carrying capabilities. In the case of our example the 87 identifies the tires ability to carry approximately 1,201 pounds.

Toyo R888
235/35R19 87 load index front
305/30R19 102 load index rear

1201 LB X 2 = 2,402 LB
1874 LB x 2 = 3,748 LB

These two pair of Toyo R8 tires will support a 6,150 LB vehicle.
http://marktg.toyotires.com/file/30029.pdf

Multiply load capacity by four tires to get your car's maximum load-carrying capacity

The higher the tire's load index number, the greater its load carrying capacity.

89 = 1,279 pounds
88 = 1,235 pounds
87 = 1,201 pounds
86 = 1,168 pounds
85 = 1,135 pounds
102 = 1,874 pounds


Typically, the load indexes of the tires used on passenger cars and light trucks range from 70 to 110.
Load Index Pounds Kilograms
Load Index Pounds Kilograms
71 761 345 91 1356 615
72 783 355 92 1389 630

87 1201 545 107 2149 975
88 1235 560 108 2205 1000
89 1279 580 109 2271 1030
90 1323 600 110 2337 1060