so here we go.
i'm gettin new wheels. the rears are a different size than the fronts. other than when i need to rotate, is there anything wrong or any side effects when driving? is there a limit to how "off" they can be. thanks guys.

 

The diameters need to be nearly exact (<1% I'm guessing). Otherwise it'll trip the ABS light and could cause emergency braking difficulty.

 

ok, then i'll use this as my example.
i'm gettin g35 wheels. the fronts are 225/45-18 and the rears are 255/45-18. he says the fronts are fine but i might as well change them. i can understand the reason he had thicker tires since the g is a RWD vehicle. but since i'm FWD, i want to put emphasis on the fronts. should i stick with 225/45's or what. the only difference is the width of the tires. i could change to 235/45's. they're both 45 series so technically they're the same height, just different width.

all four wheels are 8" wide.

 

Check the tire calculator sticky in this forum. The sidewall on the rears will be 1/2 inch taller. The entire rear wheel will be 1 inch more in diameter.

 

I think you are thinking of traction control..... and some stability systems... ABS should not be affected by tire size.... 4 wheel ABS uses a sensor on each wheel to signal the computer how to act on that wheel.... it does see wheel speeds but the main goal is to apply max brake force to the wheel with out locking it up..... traction control and stability system use the wheel speed to help you control the car.... and those system can be very picky about tire size....I run a 255/40 and 275/40 setup on my Z and the ABS works perfect

 

Agreed, my 1% was low. Your example was 2.4% diff. I mix sizes up to 3% and car feels ok even under stress. Yesterday though mixing 3.5% it tripped the ABS light while crusing. Like it sensed the different axle speeds. Worse case I mixed 26"f/24"r (8.3% diff) and the car was all over the place when braking. (Ok, air was screwey too at 16lbf/55lbr).

 

Actually the rear tire will have a thicker sidewall, as bluesbrekr mentioned. Those are 18x8 right? I would probably do a 235/40/18 if you're buying all new tires.

 

lets get into the performance aspect. With wider rears, the car rotates less through hard cornering, but you gain stability in the rear end. Alot of japanese drivers like the rear end loose in fwd setups to get the car to rotate thru turns, hence they have skinnier wheels in the back.

now on to looks: staggered setup is always nice to have, especially with a lip

and as for tripping abs, no that won't happen. Why? Because the cars at our shop run 17x8 235/40 F and 17x9 255/40 R with no problems. It won't trip anything, otherwise all rwd cars with staggered setups would throw abs lights up the a$$

 

Cars setup with stagger or diff diam from the factory have that preset in the ECU. I'm talking changing OEM diam's significantly. Those 235/255 are only 2.5% diff, and I agree won't trip anything. I'm betting changing the rears to say a 265/45 and it'll trip.

 

well, to add to this...the seller just contacted me and told me the fronts are NOT 225 but rather 235, with the rears 255. that's *less* of a difference, so that should still be fine....i think..

 

for the 5th gens, our vehicle speed sensors for the abs unit are hub mounted near the wheels. As long as you maintain the percentage near the stock diameter of the wheels+tires, it wouldn't matter as to how wide you went between the front and the back because you would keep the rotational differences relatively close to each other.

 

Another thing to consider is extra stress on suspension and brakes when you use a larger tire. This tire calculator recommends staying within 3% of stock tire height. It does sound like your brakes and suspension are upgraded already. So it might not be a problem. I'm not sure what that type of staggerred would do to your speedometer.

 

Holy ancient threads Batman.

Please look at the DATE on a thread before resurecting it from the dead.... Nov of 2004...