Depends on what kind of metal they are made of. If its a really heavy metal it will slow the car down and make mpg go down cuz it will take more power to spin the rotors.
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Winning is a great deodorant -John Madden
2008 Torch Red GT, Borla Stinger S-Type Catback exhaust, LED Tail Lights.
2003 Sonic Blue V6, 8" Shorty antenna, Smoked Headlights, GT fog lights, Sequential tail lights, Cobra IRS
Yeah Aluminum wheels are lighter and would make your car a bit quicker. And I agree with the statement that anything over 18" isn't for performance. And it depends on what kind of metal is under the chrome since chrome is just a finish that goes on top of a metal. If you aren't racing with the 20" wheels then the difference in power isn't going to be that noticeable
__________________
Winning is a great deodorant -John Madden
2008 Torch Red GT, Borla Stinger S-Type Catback exhaust, LED Tail Lights.
2003 Sonic Blue V6, 8" Shorty antenna, Smoked Headlights, GT fog lights, Sequential tail lights, Cobra IRS
if you put the typical heavy 20" wheels on your car, its gonna nearly double your unsprung weight, and slightly affect handling/braking/acceleration. also your city mpg may go down a little bit, and your gonna wear your brake pads out quicker...
It will slow down your car alot...... Rotational mass is the key, and the larger you go with your rim, the slower it will be. Check the rim weights.
We've seen as much as 2 full seconds in the 1/4 mile going from 15's to 17's. That's alot of time......
Are you sure cuz my stang has 20's and i heard that this rims only slow you .5 sec on the 1/4 mile. each of my rims including tires and air weights 65lbs. does somebody know how much a stock stang wheel weights.
the larger the rim the less traction you get, it does lower your mpg cause its taking more power to spin the wheel, and they are harder to turn.
they have this guy here with a stock green gt he has 20's all around and he tried to well pretty much drift around a pole at a light here where i live at like 3 in the morning...(no one was around) and he almost took out the light pole... he went home with a badly dented rear fender. epic fail
Are you sure cuz my stang has 20's and i heard that this rims only slow you .5 sec on the 1/4 mile. each of my rims including tires and air weights 65lbs. does somebody know how much a stock stang wheel weights.
Yes, you are way too heavy!!!!! 16" aluminum stockies run about 39#. Now, take the average drag racer who puts on a set of Welds. He has lost very little weight in the rear because of the wider rims/tires, but he's gained traction. Up front, he's lost a ton of weight because the skinnies weight about 16#. He will be faster just by losing the 46# of rotational mass up front. He may only save himself .1 at the track, but his car is well over 700hp. The more hp you have, the less rotational mass changes you will feel. Take the average 150-170rwhp V6 car, and the mass multiplies.
If you don't believe me, take it to the track with both sets of rims/tires and do the comparison. You will be amazed at difference.
Okay, I'm done talking about this subject for awhile......
Damn now im Consfused !! i dont know what to do now, cuz i love them 20"s but i dont wanna lose performance on my car
its your choice if you will be continuously racing the small ones will work, if just sometimes get the 20's i have them if you will be driving normal and sometimes hitting the gas you won't notice the weight but if you start from 0 and hit the gas hard you will feel the weight. you need to chose between look or performance. i'm actually getting 13.5 miles per gallon which is 1.5 less. i plan to buy a gt soon and i will be running with my 20's if i get less miles per gallon i for sure will put some aluminum 19's
If i put 20" rims on my stang,will that affect my performance ? 
What about those aluminum rims they are making? If I am moving up from say a stock 16" rims to 18" aluminums what are lighter?
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you need to chose between look or performance. i'm actually getting 13.5 miles per gallon which is 1.5 less. i plan to buy a gt soon and i will be running with my 20's if i get less miles per gallon i for sure will put some aluminum 19's
