garnet92

Yeah Bit, I guess you’ve got to look on the positive side – slowing the GS down give lesser cars more time to admire it as they’re being passed. Personally, I’d rather disappear quickly into the distance – leaving only a fleeting glimpse of my de-badged trunk – the vanquished driver wondering “what the hell was that white blur (with the phat wheels)”.

At 6.3, the list of cars that I’ll be whipping just got smaller – see my short bout with a WRX in the Racing forum – it was a draw – wish I’d run him with the old 17’s.

But no one should get the impression that I’d junk the new wheels to get back the acceleration – really like the looks and the handling. Looks like the wheels are gonna cost me another $1,500 … for TC/install.

GS4Will

IS,

great review and write up..but i noticed that Garnet's tyre specs are:

245/35/19+275/30/19...and you listed the spec at 245/40/19+275/35/19...would that make a difference?

thank you

cyclemax

First off, good research work IS2000! That Gtech seems to be fairly precise.

The reason you didn't get the results you expected may be because of something known as "mass moment of inertia" which is simply an object's resistance to change rotational speed.

Applying a correction factor to compare rotating weight to curb weight is a sensible approach, however it's not the whole story. A 19 inch wheel carries it's rim mass 1 inch further from the axis of rotation than a 17 inch wheel, so even if they weighed the same on a scale, the 17 would accelerate quicker, since it's mass is carried closer to the wheel's center, and thus has a smaller mass moment of inertia.

A good example of this is if you were to compare a 10lb dumbell to a broomstick with 5lb weights attached to either end. They both weigh roughly the same (10lbs), but if you were to try to spin them like a baton, you would quickly notice a huge difference.

So basically, larger wheels inherently have greater weight b/c of additonal material, tire width, etc, but to make matters worse, the added weight is always located way out at the circumference (rim and extra rubber), so you end up with more weight plus a higher mass moment of inertia.

Centerline racing wheels if running a magazine ad right now that claims an acceleration difference of 7hp by using their lightweight wheels over a heavier wheel of the same diameter. This leads me to believe there's several more hp difference when you go from 17's at 45lbs to 19's at 50 lbs. I'd say closer to 20 rwhp, but it's just an estimate. Oh, and they can make your car harder to stop too, for the same reasons.

Won't that GTech tell you the hp difference in your runs? I'd be curious to know.

IS2000

Spec Sidewall Radius Diameter Circumference Revs/Mile Diff
225/55-16 4.9in 12.9in 25.7in 80.9in 783 0.0%
245/35-19 3.4in 12.9in 25.8in 80.9in 783 0.0%
275/30-19 3.2in 12.7in 25.5in 80.1in 791 -1.0%

Ooops... my mistake, garnet's wheels are within overall diameter stock specs.

Need For Speed

I just put a set of 19" HRE 543's on my GS430, the car looks sweet, it has an agressive look like never before. It definantly needed them!
I have the SRT HFI w/Race ECU. I didn't really tell that much of a diff. once I put my rims on, it didn't seem any slower, maybe thats why.

g_lex_6

i have read that the volk gt-c's in the 18x8 wheigh only 18 lbs ! ! !
would this improve the performance quite a bit? wouldn't that be less than stock? also, do you think it would look good on an sc400?
thanks

GS4Will

GT-C would look GREAT on the SC...