20's....the good and the bad
 

getting 20s on my Z all around. 20x9 and 20x10. i was told i can just bolt them on with no modifications....besides unhooking the tire pressure sensor reciever. all of you who have 20s all around....what are the pro's and con's youve noticed so far? any problems? any compliments? thanks for any imput. just want to know what to expect

I don't have 'em, but from the one's I've seen, they make the brakes look reallly smallll. To me, they look a little lame (but I am by no means an authority on style).

Personally, I would go with 17's or 18's and take advantage of the lighter weight.

The one's I saw had 255's all around, but I can't remember the profile. 35's I think, no mods required.

-D'oh!

i got stock 18s right now, and they look small to me on the Z. i like the way the 20s fill out the wheelwell. thanks for your opinion

the only cons about 20's are they slow you down a bit & price of the tires

Re: 20's....the good and the bad
 

20x9 and 20x10? You'll probably have to roll your fender.. If you are interested in all show and not so much go, then by all means go with the 20's and have a ball :)

--mike

If one does put 20s on the z how will the driving characteristics change (cornering, speed, comfort, etc. )

Thanks

Cornering: You should experience slightly higher cornering prowess with the wider tires and lower flex sidewalls. However, it is possible that the bigger wheels & tires will be more prone to being upset by a mid-corner bump or imperfection.

Speed: You are adding weight, worse yet you are adding rotating weight. It will be more difficult for the engine to spin those big boys - slowing acceleration. Also, by making the outer diameter of your tire larger, you are essentially making the gearing of your car taller - this also slows acceleration. I just saw something on "Sports Car Revolution" (or some other show like that) that added a big brake package to a car (RSX I thnk). They dyno'd it before and after the install - and the brake package sapped 12 wheel hp from the car. You are essentially doing the same thing.

Braking: Everything that was mentioned for speed, but in reverse. Your stopping distances will increase.

Comfort: Well, as far as ride comfort, 1) you have less sidewall and therefore less sidewall flex so a higher percentage of each bump gets transmitted to the suspension and therefore to your butt; 2) since more of each bump gets to your butt, it's obviously also creating more stress on the chassis - also the higher weight of these wheels and tires means that when they are forced upward by a bump, it creates even more stress on the chassis - these factors combine to cause creaks and rattles faster. The good news is that with your new rims, you have essentially lowered your RPM at a given gear and speed, so you should experience better highway fuel economy.

how much actual difference is there between stock 18s and 20s with 30 profile tires? probably not much-as far as diameter. weight, yeah i can understand

Don't know, but here's an article that has some bearing on the issue.

http://www.sportcompactcarweb.com/features/0208_scared/

Thanks BDM. Great info!

The car was designed with 20" in mind
 

Look at the show car it had 20's. I think anything other than 19's looks lame, the wheels sit inside the wheelweels like an old friggin bug. Everyone who saw my car when it was new with the 18's said " dude, looks cool but you need some bigger(wider)wheels to fill out those wheels wells" 19's are a good compromise and if you plump for some good ones they're light also. Looks are half the battle, don't give me this "it's all about performance" otherwise you would have got an STI . Most people who dog 19's do so because they can't afford a nice set of forged ones. On another note, what's with putting all this add on body kit stuff with stock wheels, ARGGGGHHHH talk about lame looking that's soooooooo rice.

Re: The car was designed with 20" in mind
 

I'll agree to some extent if i had a Z i wouldnt go bigger than 19's but 20's on a G35 is a must I get too many people telling me that my Iforged Evos look like 19's some even say 18's:mad:

I had 20.9 and 20.10 Axis seven mods for a couple of months and have only noticed better handling/cornering. I compensated for the weight issue by slapping on the lightweight flywheel reduing the rotational mass. The stock 17in tires/wheels are heavy SOB's and the new tires/wheels were about 25lbs more. 25.lbs is nothing compared to adding large stereo boxes with amps and subs or polly body kits. I haven't noticed any decrease in acceleration buy maybe a slight bit in braking.....but nothing to raise a brow at. Cosmetically, the 20's fit perfectly with the Tein S-Tech springs. The height of the car is pretty much only .6in lower than stock so the center of gravity is retained nicely. However because the wheelwells are filled, the car look lower than it actually is.

25 lbs rotational wt is like 250 lbs of dead wt in the car, I can tell a HUGE difference in accel when I have a passenger, so yes, it is a big deal

How is 25lbs rotational weight equal 250lbs dead weight? That seems way too excesive. Rotational weight takes into consideration momentum and inertia unlike deadweight. I've had some big people in my car, not HUGE, but good sized but there's a differenc in having a 250lb man in the passenger seat concentrated all on the right side of the car, and 25lbs distributed equally to all four corners.

its a fact that a 20'"or even a 19" will slow you down, I raced my friends 6mt on his stock 18's vs my 6mt with 20's both in 4th gear flooring it at the same time the stock G with 18's pulled on me by about a car.

Good thread. So would 19's be classified the same as 20's ? as far as cornering, speed, braking, comfort ? I'm thinking about getting 19" Volks, now maybe i will lean more toward the 18" nismo wheels. Any guidance?

Weight on a wheel affects the wheel's rotational moment of inertia. The moment of inertia is a measure of how the weight is distributed on the wheel. The common wisdom is rotational weight counts twice that of non-rotational weight. That's because to accelerate, you have to pick up translational momentum, which is what you gain moving down the road, and you also have to pick up angular momentum, which is what you gain spinning a wheel. If I was constantly driving up an incline, the rotational weight of the mass would come into play more than driving on flat surfaces. If I lived in San Fran....Whoa. The only aspect that I could see causing serious problems is the additional weight causing rolling ressistance.....but again on a car that's 3200lbs, 25lbs is minimal.

Sorry to say but there are so many more factors involved than just saying it's a fact. Like all wheels, 18in, 19in, & 20in wheels come in different weights. What was the weight of your wheels? Is your friend a better driver, did you hit your shift points at peak RPM(if you shifted late, the car slows because of loss of HP). Just by saying "It's a fact" doesn't mean because you lost because of the wheels. If you added wheels that were heavier and you were concerned about performance, adjustments should have been made. The whole weight issue goes farther than tires or wheels. Did you have a full tank of gas?......Did he half a quarter tank? Most people on this site know for a fact that a lot of 19in wheels(especially Volk) are lightweight so this disproves your "fact" from the start. What type of 20in wheels do you have?


For a bolt on performance.....19 Volks are the way to go...LE37/TE37 personal preference. If going with 20's you'll have to make adjustments. The stock wheels(except for Track) are heavy along with heavy tires. Stock 17in---23lbs FR, 24lbs-RR, Stock 18in--26.5lbs


Tires(not including air)
17in---28lbsFR 29lbsRR
18in---28lbsFR 30lbsRR

are 19's the same as 20's??? I don't know, are 18's the same as 19's???

The rotational wt matters much more than static dead wt in the car. My 19s are 8-9 pounds lighter than my stock 18s, but I would be lucky if I didn't lose performance, since most of my wt is distributed to the parameter. Maybe I have a slight advantage (toyos are light), maybe a slight disadvantage (I have 10" wide rear wheels). The other problem with 20" wheels is that most of them are more for "show" and less "go", meaning most of them are heavier, chrome, and less high performance oriented then wheels under 20" (this is a generalization).