im not going to run them at the track .. but you never know what happens to pull up next to you at the stop light

 

PU

 

315's usually go hand in hand with 11 inch wide rims though. That's what I was inferring.

That said, I'm not at all against huge wheels. They just look so damn good.

 

To each his own, but i think you bought the wrong car...Im sure theres a nice used escalade for you to go BLing Bling in...spen the 1200 on porting your heads and then go kick some real a$$ and show what a Z was made for....

 

am going to port the heads and put a xe224/230 cam kit in it. but why not look good doing it? and girls dont care how fast your car is.

 

As OldStroker had already pointed out.... it is weight AND size. The wheel/tire combo aborbs energy when you acclerate it. How much it absorbs (and steals from the power you put to the pavement) is a function of the polar moment of inertia.... and that is a product of weight, and the distance the weight is located from the axle. Get a thin section wall tire on a large diameter rim, and the mass is moved farther from the axle. More HP to bring it up to speed. Basic physics.

The dyno test at ws6.com is a measure of the potential loss.... he lost 3.5HP just because he made the wheels wider... If you move that mass farther from the axle, you are going to lose more HP... how much... it can be calculated.

I was in a shop the other day and they had a 23" diameter wheel off an Escalade.... I would guess it was close to 90# with the tire...???????????

Some other considerations with 20's:
-more susceptible to rim damage from potholes
-harsh ride
-lost HP
-high cost for tires
-negative impact on handling with a solid axle suspension... the cars that come from the factory with huge rims are all independant rear suspension, with more compliance to make up for the short/stiff sidewall.
-even a 245/35-20 is an inch larger than the stock wheel/tire... raises the car 1/2" further off the ground, pushes the tires up into the wheel well with more potential for rubbing, had the same effect as going to lower numerical rear axle ratio.

Lot of negatives, and the only positive is highly subjective....

 

*giggles like a catholic school girl* yep, i got the vette 18's...allllll around. yeah baby, yeah!!!

 

Another vote for sticking w/ the salad shooters. Plenty of traction & cheaper tires. Plus, I kinda like the way they look (sleepers).

 

I have 15" rims and 28" tires. great for the 1/4 mile. Terrible for corners.

 

- My 20's are lighter than my 18's

- Handling, traction, and ride quality is unbelieveable Handling in the twisties can't even be described, and I finally got rid of the notorious F-Body wheelgap.

- I am the first F-Body with 20x10.5 on all 4 with 35 series tires, and I am stoked about it even the offset is better than I had imagined.

- My tires will be around $600 each season

I agree with the following Injuneer posts:

-more susceptible to rim damage from potholes
-high cost for tires
-even a 245/35-20 is an inch larger than the stock wheel/tire... raises the car 1/2" further off the ground, pushes the tires up into the wheel well with more potential for rubbing, had the same effect as going to lower numerical rear axle ratio