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Discussion Starter · #1 ·
If I were trying to get the best 1/4 mile, and had the choice between 17*7 ETX belliso (chrome - heavy) with Falken GRB Z rated tires on them (very sticky); or my stock GT rims with new rubber on them (all seasonals).

Which do I pick? The light stock rims that slip easy (will lose time there). Or the heavier alloys that are harder to spin, but are sticky. Please note that I have enough power to smoke the Falkens.

My interpretation of all this is: its such a close call that only empiral data will tell the difference: i.e. I have to do three runs with each of the wheels and compare results. Or at least one run after I've had some practice.

But based on your guy's time trial experience, what wheel/tire combo would you pick if you wanted the best result? :blob6:
 

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I'd go with the stock rims with new rubber on them. 17s will make the gearing taller plus it's harder for the engine to turn them because of their diameter and weight. If you want even better results, get some 14s of an LX and take the hubcaps off and throw those on your car.
 

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For best acceleration you want the lightest wheel possible. Really in my oppinion you should always get the lightest wheel possible in the size you want. I can't remember the calculations but essentially if you can lighten up anything in the drivenline/wheels you are freeing up all sorts of power.

The smaller the wheel lower the gearing thus better acceleration.

The obviously you want the stickiest tire you can get. Most cars can spin just about any tire. The trick is to launch just below that point and keep it there.
 

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Stock wheels with very low front tire pressures and max pressure in rears.

As long as the overall diameter of the wheel-tire package isn't any larger on the 17's there won't be any difference in gearing.. but the difference in inertia is astounding. Remember you're taking a much larger rim and putting it 1" further from the hub... that's like 300lbs of dead weight.

You only need traction for the first gear or two.. and you can just ease off the right-most pedal to compensate.
 

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Discussion Starter · #5 ·
egtdude said:
I can't remember the calculations but essentially if you can lighten up anything in the drivenline/wheels you are freeing up all sorts of power.
Wow that sounds like a profound statement. Especially when it comes to my car. Cause right now I'm running heavy 17 chromes and on top of that I'm running 2 in" 3 to 4 lb spacers on each wheel!!! Imagine how much power I must be losing on the drive wheel (driveline loss) with those spacers on!!!

Assuming your statement is true: "freeing up all sorts of power". The spacers are mainly for looks (wide body) and some handling.

I'm really curious to take my car to the all ford track meet now. I'm thinking I'll do it. I have a set of stock rims with practically new rubber on it.

Thanks for the input guys.

The driveline loss was calculated on my car before and it was supposed to be HUGE. It didn't make sense to me because if it was infact that much, my car was pushing 160 hp at the flywheel and to me that was impossible. I'm guessing my car is pushing about 140 hp at the flywheel; 112 hp at the wheel.

Only the the track will tell what its really pushing. So maybe I should go. At least you guys have convinced me to take off my spacers and put my stock rims back on, and Beaverboy has told me to hyper inflate my rear tires to maybe 40 psi.

Front tires to maybe 29 psi?
 

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it is true... everyone knows removing weight from a car free's up acceleration, cornering etc. Now for the driveline/wheels etc not only does the engine have to move it down the track/raod but it has to get it spinning as well. The lighter it is the less Torque it takes to get it spinning.
 

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while we're on the topic, anyone know if a 13" or 14" wheel will fit over egt brakes? and if so, do you know of any wider than 6" that'll fit on? i want some short fat meat..
 

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14" will deff fit (same brakes on GT as on scorts w/ 14" steelies and alloys, I believe). Nobody seems to know for sure if 13" wheels will fit or not (I've asked on several occasions).
 

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whooohooo I know something beaver doesn't! :)

so yeah for autocrossing Keizer I think it is. Alluminum. I can't remember if it is 2 or 3 piece. You want the bolts on the opposit direction. Then they will fit with no trouble.
 

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James92Scort said:
I'd go with the stock rims with new rubber on them. 17s will make the gearing taller plus it's harder for the engine to turn them because of their diameter and weight. If you want even better results, get some 14s of an LX and take the hubcaps off and throw those on your car.
How does having a 17" whell make a difference. The wheel tire combo that I have = the same diameter that the stock 15 wheel tire combo that came with the car. The only differnce that I have is a lighter tire and lighter rims. So I should be able to grip better and go faster.

Sajeevan If you are looking for a light track set up, look at these. http://www.axiswheels.com/maglite.html

14lbs for a 17" wheel is nice.

Jason
 

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The difference in the weight of the spokes on 15" and 17" wheels isn't too much, so lets ignore that for a moment. Lets say we have two wheels, 15"x7" and 17"x7", that are of the same design.

The big difference comes in that the rim gains 3.14" .. that's a 14% increase in rim weight.. Then, by putting that weight an extra 1" out further from the hub you're increasing the effective inertia of that rim by another 14%.

Lets say the 15" wheel's inertia has a unit of = 1

1 * 1.14 * 1.14= 1.30

By increasing the size of the rim from 15"x7" to 17"x7" you've increased the amount of power the wheels soak up by 30% (not counting the spokes).

I'll be happy to show my math if someone is interested.
 

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darnit I've been searching for that info for a while! I had seen it translated into HP at one point too. Any chance you could give us the full math treatment?
 

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Try ROTA wheels on the front 15x6.5 40mm offset. Only twelve lbs each.
Use BF Goodrich Drag Radials on the front they're R-compound and they can be found for about $110 per tire. 15x205 will fit with no rubbing.

On the rear go with the narrowest & smallest 4x100 (assuming it's a 2nd gen) bolt pattern wheel you can find.

That's my 2 cents worth.
 
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