Rims size, change in performance Options

[Mr_E]

Agreed. To get aftermarket wheels that are lighter than stock usually costs serious money.

[94GT]

Here is the bottom line: Your performance will suffer if you switch from 15's to 17's. When you displace the mass of the very outside of your rim from 7.5 inches (15's) to 8.5 inches (17's) from the center of the hub, it requires your car to work harder to rotate the wheel. (I don't remember the equation, so I can't tell you how much since I brain dumped all that after college...) Another area of concern which has prevented me from upgrading my wheels, is that if you calculate the sidewall height, I have not been able to find a rim and sidewall height that exactly matches the total diameter of my current 15's (with tires mounted). They all go up by a bit. This will change your speedometer anywhere from 5 to 10% depending on what you do. A lot of people upgrade their wheels, and I haven't yet heard of anyone having their speedometer recalibrated, so people who have done that are slightly off on their speedometer and odometer. You're actually going slightly faster, and slightly farther than indicated on your gauge. Until I find a mechanic who can recalibrate my speedometer when I upgrade the wheels, I'm just going to stick with the stock 15's. Anyone ever have that done?

[jgreening]

Another area of concern  which has prevented me from upgrading my wheels, is that if you calculate the sidewall height, I have not been able to find a rim and sidewall height that exactly matches the total diameter of my current 15's (with tires mounted).  They all go up by a bit.  This will change your speedometer anywhere from 5 to 10% depending on what you do.  A lot of people upgrade their wheels, and I haven't yet heard of anyone having their speedometer recalibrated, so people who have done that are slightly off on their speedometer and odometer.  You're actually going slightly faster, and slightly farther than indicated on your gauge.  Until I find a mechanic who can recalibrate my speedometer when I upgrade the wheels, I'm just going to stick with the stock 15's.  Anyone ever have that done?
[right][snapback]255088[/snapback][/right]

You are incorrect on the 5-10% figure. You can use 205/50/16's or 205/45/17's and your speedometer will read .6% or 1.6% too slow respectively. That means when your speedometer reads 60mph, you will actually be doing 60.36 mph with the 16's or 60.96 mph with the 17's.

[SlowCelica94]

They are 15 lbs....

[Coomer]

I don't know where you guys are getting your stock wheel weights from... but stock 15in alloys probably doesn't weigh more than 18 pounds a piece... and that's the very max.  I'd bet they're only about 15-16 pounds. 

Basically... if you're getting wheels over 17 inches... they're not gonna be performance lightweight wheels unless you're paying over 2g's for them... the cheapest may be some kosei k1s which can still weight as much as 17-18 pounds in 17 inches.  If you want lightweight wheels... 7th gen GTS wheels are nice and light... that, or get some 5x114.3 camry hubs pressed onto your spindles and buy some Rotas.
[right][snapback]255042[/snapback][/right]

What would be the point of going to 5x114.3? They make Rotas in 5x100 in 40 and 48mm offsets.

[Kwanza26]

What would be the point of going to 5x114.3? They make Rotas in 5x100 in 40 and 48mm offsets.
[right][snapback]255122[/snapback][/right]

Only in Subbie offsets and only in 17inches+... I personally would rather roll some 16in grids or something else... ;]

[Consynx]

just wanted to back my comment up...lol

19lbs is a step in the right direction, because i dont really feel that a sports car should be rolling chrome wheels that slow you down unless going to the Big Pimpin look

[Mr_E]

Here is the bottom line:  Your performance will suffer if you switch from 15's to 17's.  When you displace the mass of the very outside of your rim from 7.5 inches (15's) to 8.5 inches (17's) from the center of the hub, it requires your car to work harder to rotate the wheel.

You're assuming that the rim is heavier than the tyre.

(You're correct)

However, bigger rims means less sidewall flex. This is a good thing.

[gnetik]

Less sidewall flex is better because of less flex of the tire which leads better cornering? Oh, and I was doing some research on wheel weights and was able to find this:
http://www.mysportscar.com/features/wheelweight.htm#M

This is a list of a lot( but certainly not all) wheel weights. And by the way, has anybody ever heard of akita rims? Are they light weight wheels or at least decently light?

[Mr_E]

Good list.

And that, ladies and gentlemen, is why I bought superleggras rather than supertourismos......