Nearly all 18" rims are going to be way heavier than the stock rims. Stock rims are around 18 pounds.... most 18s are going to be around at least 23 pounds, probably more.

 

key word's nearly all 18"

 

hmmmm, i dunno man.

What make and model of rims did you get?

 

konig trouble ..light alloy

 

ok... more info on rotational mass.

The larger rim you use, the smaller the sidewall on your tire needs to be. What this does is put more and more of the mass of your rim and tire setup at the very edge of your wheel. By concentrating all the mass there, you are actually making it HARDER to spin the wheel.

Watch an ice skater.. when they have their arms out when they spin, they usually have a nice slow rotation.. but all they have to do is tuck their arms and legs in.. and they easily double their rotational speed without increasing their momentium. NO MORE ENERGY was spent in going faster, but they picked up double thier intitial speed.

A 16 inch rim, with it's taller sidewall, actually brings the mass an inch or so inwards towards the centre of the rim. It may not seem like a lot, but in a race where every hundreth of a second counts, it can make a BIG difference. Why do you think they make drag tyres for 13 inch diameter rims?

 

putting 18's on the car is bad news power wise. I had 17's on my car and they slowed me down some, I can only imagine 18's

 

For example Hyundai Motorsport Team use 15x7.5 " rims with 225/45 ZR15

Think about it.
That Tiburon 2.0 n/a run 0-60 ph for about 6 sec.

 

Idk if its to late to bring this up but Ive been riding on 18s for almost a year and ya the ride is a little brough but mine do not rub at all and i havent noticed a significant power loss. I love the way they look but I think if I were to get new ones I would go wtih 17s only because tehy are so much easier to find and you cna get crazy deals on them.

 

^^^ Go to the track and tell me the same, if you have 15's and then your 18's
Obviously with tires in the same condition.