What do you mean by going to FI?

Okay, this is what I'm guessing. Acceleration will be slower due to the increase of rotational mass. So.....only the weight of the rear wheel should be factored in this as the G is rear-wheel drive. The 20x10 rears I'm looking at weigh 30lbs. Since it seems no one knows the weight of the coupe 18s I'm going to have to guess they're 22 pounders, which will mean a total of 16 lbs additional wheel weight. 16 x 5(q45tech's factor) = 80 lbs heavier trunk weight. If that's the case, I can live with that as I myself only weigh 160 lbs. Also, I've never been on the track and probably never will be on the track, so I probably will not notice the difference as you guys that do are probably very particular about your car's performance and probably do more than ordinary day-to-day driving. Am I right? I hope. (I'm really trying to sell myself on the 20s here)

Forced Induction

Coupe wheels are 24.5 lbs. You have to consider the weight of wheels + tires, not just the wheels.

Sounds like you are leaning toward 20s. Get them. Any performance loss is going to be small (I have lighter 3 piece 20s myself and don't notice a difference). Besides, do you really drive around full throttle all the time? My car spends more time parked at stoplights than it does wide f***ing open. How about yours?

It won't be small. It will be a noticeable large performance loss.

My 19s are light for 19s and I still noticed my car got much slower.

It feels like I have 2 people in the car and a trunk load of autox gear.

No, all 4 wheels need to be included in the factor, unless your car wheelstands when launching. Seriously though, the car has to accelerate all 4 wheels up to speed, both linerly and rotationaly so all 4 wheels count in rotating mass.

what is so special about IF 20s that make it better than other 20s?? wheel design???


thanks


mahdi

Same deal. Drive to work and back. That's all.

I have 20s and I can feel the difference when accelerating. Not enough for me to regret getting them though.

Did you compare weights from stock to the GT7's? Just curious what they weigh in 19 and 20.

The wieght of a spinning mass is called centrifugal force, and the equation to find it is F = ((m)(v squared)) / r where F= force, m= mass (of the wheel), v= velocity, and r= radius (of wheel). So, as you can see, the speed plays a massive part in determining how much weight you will be pulling. This equation is for, say, a ball being spun held by an anchored string, meaning that the bias of the weight's location on the hub can change the force dramatically. i.e., If the outside of the rim were to have 45% of one rim's weight, it will not rotate with as much force as one with 60% of the weight on the outside. This means that tire weight will play a large part in your rim's rotating inertia, but using an unltra low profile tire with an extra inch on the rim may not be benificial since I'm not exactly well versed in their specific weights. The best plan would to be to go with lightweight 18s and very nice tires ofr performance, but who wants to buy aftermarket 18s for a luxury sports car when they have a choice for larger? For me, I think I'm just gonna grab some some summer ultra performance tires for the stock 18's.

I'd go with 20s. If you really wanted to go that fast, you'd be in an Evo or STi.

Or just get the 20's and go FI. The Evo and STi are nice cars but I don't like the interior on them. The G is a whole different class of car.

19's are big enough for me. with a drop it looks perfect