Dr. Evil

Yes I searched but found a bunch of stuff about everything else besides the effect of lighter wheels/tires on your et and trap speed. I now have a set of et streets on some 16" F body wheels. Each one weighs 5.5lbs less for a total of 11lbs less rotating weight. Is this enough to make any difference at all in et and mph? Just curious. My track opens soon and I'll find out that way for sure but itd be nice to have an idea of what, if anything to expect.

FWIW, I went from stock sawblades 17x8.5 with 275 BFG drag radials to the 5 spoke firebird 16" wheels with MT ET streets 26/10.50/16

REDGAR

I don't think a formula exists that will tell you that and the way of proving the should a small weight change is too difficult with so many variables one pass to the next.

You even changed tire size and type which is going to be hard to predict it.

Best bet is the 100 lbs per tenth is pretty regular for our cars so if you dropped 11 lbs then .01 to .02 is about all I'd go in looking for. Could be better. Could be worse. ET Streets tend to have lower mph due to more drag so you may not see a mph gain.

ralph

Changing from my full size front tires (100lbs) and skinnies (45 lbs) i picked up about a tenth.

Mr Mojo

Stock 17 x 8.5 sawblades with a 255 tire weighs 46 lbs.(Michelin Pilot XGT Z4-best damn tire there ever was)
Stock 17 x 9.5 sawblades with a 285 tire weighs 47 lbs.(same brand as above)

AFS 5 spokes 17 x 9.5 with a 275 tire weighs 51 lbs(Dunlop SP8000)
AFS 5 spokes 17 x 11 with a 315 tire weighs 52 lbs(same Duncrap tire)

Difference? With the bigger heavier tires the car slowed a bit in ET and mph. I can't gauge exactly how much because I don't feel like digging out the timeslips.

With Weld Prostars 15 x 3.5 with a 165 tire, weight was 24 lbs.
Weld Prostar 15 x 10 with 275 drag radial weighed about 38-41 lbs(I forget exactly, but the CCW rear with ET Streets weighed exactly the same)

CCW fronts weigh 36 lbs.

Car slowed a lot. 60' time are slower by .05-.10
ET roughly .15-.30 slower.

In some cases weather conditions played a part, but ever since I put the CCW's on, I haven't run below 13.00 and my best on the car is a 12.50(in great weather). Average runs were 12.75-12.80 with the Weld setup.

AU N EGL

There is a fairly long drawn out formula for determining wheel wt and rotational acceleration.

what it comes down to is each lb of rotational mass removed is worth ~ 6 1/2 lbs removed out of the car.

Force is often defined using Newton's second law, as the product of mass m multiplied by acceleration.

F=ma

and

F /m = a

so reducing the mass ( m ) of the car and keeping the Force constant, acceleration should increase.

i e reduce the wt of the car or wt of the wheels and acceleration increases = lower times

GrandSportC3

I went from 50 lbs/each front wheels&tires. to front skinnies (20 lbs/each) and went from 45 lbs rear wheels&drag radials to 37 lbs for wheels&bias-ply slicks.. Picked up .25 - .30 with that change.

Fartpipe

What I feel with my findings is this.
100lbs off the car is approx .10 and approx .75-1.0mph
100lbs of ROTATING weight is multiplied by 3. My results show 100lbs of wheel weight off gains 3mph/drops off .30 in the quarter on similar air condition days with same track and similar prep.

Dr. Evil

[QUOTE=AU N EGL;

what it comes down to is each lb of rotational mass removed is worth ~ 6 1/2 lbs removed out of the car.



[/QUOTE]


This is what I was looking for. I'm familiar with the 100lbs = 1 tenth 1mph rule but was wondering about unsprung weight, specifically the rear wheels and tires.
Every little bit helps and if you cant find 20 hp in one place find 2 hp in 10 places.

Dave-T

Does anyone know how much the C5 CCW drag pak weighs? This would be the radial package with 17's in the front and 16's in the rear.
Believe it or not CCW does not know how much there own product weighs.

PDQUIK95

Dave,
I should have my new front 17" CCW Classic 4.5" drag wheels delivered next week. I'll let you know how much they weigh then. Had the M&H skinny tires mounted so it will be a combined weight.I'm running the 17" x 10.5 wide Fikse FM5's in the back with Nitto 315/35 DR's.Your right about CCW. They couldn't tell me the weight of the wheel either.
Rick