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Discussion Starter #1
Every since I put my new wheels on my car my take off has dropped dramatically. [?|] [?|] I love my wheels but has anyone else noticed a large decrease in take off with big wheels?
 

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I have not since I am still on the stockers.. but its a known fact, larger heavier wheels mean it takes more for the engine to get them moving thus slowing you down. Its a trade off.... how much do they weigh?
 

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when i had my 18 in oz's i had no problem. they were pretty light for 18s.
 

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when I went to svt 17's I did notice some loss
i noticed handling was better, but that's prolly due to the
good rubber on them, I since put a sri and a tb and it feels great now
 

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Welcome to the wonderful world of physics. Those heavy new 18's are not only heavier they also have a greater polar moment of inertia. Basically they act like a big ass lever working AGAINST whatver it is that you want them to, be it accelerating from a stop or braking to try and stop.
 

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If the diameter of your new wheel/tire combination has increased, that is, the rolling circumference, you have also increased your overall gear ratio for every gear.
 

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doesn't oscar jackson have a dyno about this on his site?
 

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see when I went with 18's, the rubber was suck a low profile, it only increased my overall circumference by an 1/8 of an inch over the stockers, they do weigh a little more, like half a pound, but i never really felt a BIG difference, other than handling b/c they're a 1/2 inch wider and very sticky tires.
 

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That's a very important part to consider when buying wheels and tires is weight. You dont wanna go to heavy, but the lighter the better [:D] That was my biggest problem with finding the right wheels was weight, and i didnt want to pay 220 per wheel!! (5zigen FN10R-5's)
 

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I thought about this when I bought my focus, I would love to get some bigger rims but unless I mod the car to compensate for the added rotational mass it would actually de-engineer the car.
 

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Discussion Starter #13
Thanks for all the input, I guess I should of pointed out the weight isn't a large increase from the stock to these 18s. I know the larger the wheel, the slower it takes to get them going.

As far as mods go, all mine have been cosmetic base. I only have the 2.5 cat back exhaust to help the performance. Does anyone think with a MM CAI would get me back to the take off I once had?
 

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It will certainly help.
 

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Recommend reading this article

Hi,

Much of what is important to know about wheel size and how it affects performance has been covered by the many fine posts already made in response to your observation that your car became slower after you added the larger wheels.

Mike Kojima wrote an extensive ariticle on this subject which can be found here:
Extract:
  • "Generally, it's possible to stuff a tire two sizes larger than stock into most cars' wheel wells. For instance, a car that came with a 185/70-14 tire on a 5-inch-wide wheel can usually accommodate a 205/50-15 on a 7-inch-wide wheel. Putting the tires on a wheel of the recommended width is important as well.

    Going up an inch in wheel diameter and running a lower profile tire is a good thing. A lower profile tire has shorter, stiffer sidewalls, which improve response to steering inputs and hold the tread flatter to the road surface during cornering load. However, it can be overdone.

    Ultralow-profile tires are more sensitive to suspension tuning and camber changes. And stiff sidewalls don't conform to road surfaces easily. This makes ultralow-profile tires sensitive to shock, as the short, stiff sidewalls have very little compliance. Harsh surface inputs can make these tires skip and hop across the surface instead of digging in and finding grip. Large wheel and tire combinations also increase rotating and unsprung weight.

    For example, most enthusiasts driving small-bore four-cylinder front-wheel-drive cars run 17x7-inch wheels with a 205/40-17 tire. The big wheel and low-profile tire look cool, but this combo is too large and too heavy for optimal performance. Hard-core track geeks driving these same cars almost always fit a lightweight 15x7-inch wheel with a 205- to 225/50-15 tire.

    Huge wheels also increase your car's final drive. Their added weight increases the flywheel effect, slowing the car's acceleration and increasing load on the brakes. This means wheels larger than 18 inches are rarely used for performance, so even for large cars, 18 inches is the maximum practical wheel diameter. There are few choices for DOT-legal race tires larger than 18 inches anyway.

    Huge wheels can greatly increase unsprung weight-the weight of the components that aren't suspended. This includes the suspension arms, brakes, half of the shock absorber and the wheel and tire."
 

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it also depends on if the wheels were cast or forged. forged wheels are MUCH lighter than cast. go to www.centerlinewheels.com if you want good lookin chrome that's LIGHT. the 17's i bought from them actually weigh LESS than my stock 15's
 

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Shadowrunner said:
it also depends on if the wheels were cast or forged. forged wheels are MUCH lighter than cast. go to www.centerlinewheels.com if you want good lookin chrome that's LIGHT. the 17's i bought from them actually weigh LESS than my stock 15's

So do the Rotas that Rob sells on ZXtuner.com. I actually checked tire sizes and wheel weights before trying to make a decision. Using the Rota Slipstream 17's and Continental 215/45 tires the wheel and tire weight was only 1 lb more than my stock alum 15's which weigh 36 lbs according to the bathroom scale.

Forged is stronger, but Centerline doesn't post the wheel weight [:(]
 
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