would there be any negative performance effects (slower 0-60 times) if i upgrade to 18x8.5F and 18x9.5R wheels with 245/40/18F
275/35/18R tiers? my main aim is to have better 0-60 times and better looks
rims will be around 18lbs each
Please comment! thanks!!!

No negative performance effects... your talking about going from a wheel that weighs 23+ lbs. to one that weighs 18. Your losing a significant amount of rotational mass which will increase performance and the wider tires out back will grip more. So the answer to your question is NO!
-GP-

Trance-

I agree with the rotational mass not being an issue with the wheels, but the tires are different.
If you want to keep as close to the OD (outside diameter) as possible ,try 245/45/18 and 275/40/18. These are both 26.8 OD (Pilot Sport tires) stock OD is 26.4 or 26.5 depending on the stock tire. The 245/40/18 has an OD of 25.8 which is smaller, but a farther deviation from stock.

If you are planning to possibly have to make modifications to the speedo and VDC and everything else to do with the traction control and ABS then by all means do the smaller size OD if you wish.

Hope this helps!

Trance - you may not want to run what he recommends....as that setup will most likely rub in the rear. It's been confirmed that 275/35/19 tires rub in the rear, with a stock suspension. Follow my math:

275/35/19: 275 x 0.35 = 96.25mm = 3.79 in
3.79 in x 2 = 7.58 in.
7.58 in + 19" rim = 26.58 in (larger OD than stock..plus you're running a much wider tire, so this rubs)

Now he's recommending 275/40/18...following the same math as above, but with an 18 in. rim yields 26.66 in. (or 26.8 as he says above). You may want to ask around before going w/ that setup, unless you want to roll your fenders. Obviously the offset will affect this as well.

DaddysG35 - I'm just trying to prevent him from making a mistake...

Let me know if you want that link where 275/35/19's rub.

Good luck.

One also has to check the tire weights. Even if the wheels only weigh 18lbs. (that is pretty light if you are referring to the 18 x 9.5" rear) A 275-40-18 is going to have some heft to it

That's wrong period

Scenario 1)
If he goes from a stock 17 x 7.5 to 18 x 8.5 / 9.5 ; he is gaining tremendous amount of rotational mass ~ K * M * R^2, which originates mainly from the increase in radius. An increase in rotational radius will have an impact of ~(delta R)^2 that is actually A LOT when compared with the decrease in Mass from 23lb to 18lb.

***(K is a constant depending on the distribution of mass, in this case the mass mostly resides in the outer rim; M the mass; R the radius of rotation)

Scenario 2)
If he goes from a stock 18 x 7.5 / 8 to 18 x 8.5 / 9.5 ; even though the radius is constant in this case, the increase in Rim width will add rotational mass (please notice that I mean rotational mass, instead of the total mass of a rim that one will argue about). Moreover, the widened tire will also add rotational mass to the formula, which decreases the 0-60 or generally acceleration performance

Yet, handle wise, this should be a good upgrade; but the fact is, you are going to do worse in 0 - 60 or 1/4 mile with your intended upgrade

Cheers

so what would be the best configuration for having better 0-60 times?
does that mean that the 18" rims are out of qustion godmans? stock sedan are 17s
I might just go with forged rims if the weight is an issue
the tires will be Toyo proxes T1

Bro,
i agree with some of what your saying but even though you're increasing the diameter and the width you're still losing weight while increasing traction which is important on the track. It's NOT going to make his 0-60(which doesnt meant $hit) or 1/4 mile worse.

So trance, no 18's arent out of the question, if you want the best performance on the track then go with some light weight 17's but 18's will still be a good choice if you want looks and performance.
-GP-

You guys are splitting hairs. Just add some NOS and stick some 20 inch spinners on.

Get the plenum spacer and your staggard 18" wheels and of course a z tube wouldn't hurt you can get all of those modds for a reasonable price and not only will your handling improve so will your 0-60 times. Shopping for wheels can improve your 0-60 times but you will gain more by focusing on performance and handling in addition to 0-60.

Jimmy he is talking about getting 18" not 19"

ive got the Z tube and stillen CAI sitting here waiting for the weather to get nice so i can put them in hehe

It's my undertanding that the only way this config will rub in the rear will be due to wrong offsets. If proper offset is chosen for the rear, I believe +45 and above to be conservative, he'll not encounter any problems.

I was going to quote Jimmy about this and say the same thing. However, I have a 45 offset on my rear tires and they rub with a 275/35/19. However, my tires are not being damaged, they simply make a noise when hitting the fender. And it is only by an 1/8 of an inch, I need to slightly bend in the fender with a bat and this should solve it. I'd say something below 45 and over 38 should prevent rubbing.

im going for +38 front and either +42 and +45 on the rear...
its not very easy finding a company that ships to Canada