I am curious if I traction control will be thrown off If I use 255/40/18 on the rears my 2003 Coupe 6MT , while keeping the fronts with 225/45/18. Will the lowering of 5 series from the front and the rear affect traction control? My rears are baldening out and want to widen out the tires a bit on the OEM rear wheels.

 

go with 235/35/19 and 255/35/19 rear.. never had a problem an it look nice too with 35 series all around. nitto invo tires btw

 

I'm running the OEM 18s for my 2003. I actually like the extra cushioning from the 45 series in the front.. but I'm curious if it would be OK with 45 series in the front and 40 series in the rear. I'm not sure will that throw off the traction sensor

 

i also have a set of 18's tsw 245/40/18 275/40/18 rear with nitto Nt555 tires an never had a problem with it.. my car is drop 1.2 (f) and 0.9 (B) btw. Right now im running my OEM 19" with 35 series all around nitto invo.. i can post some pix with my 18" and 19" if you like to see it.

 

your tire series match front and rear... I'm talking about higher height (45 series) front and then reducing height to 40 series in the rear.

So the setup will be
40 Series Front
45 Series Rear

difference of 5 series front and rear... And would there be any problem with traction control sensor...

 

255/45/18 is a better fit for the rear, but if you are keeping a 225/45/18 on the front, you are better off sticking with a 245/45/18 in the rear. If you go to wide in the rear compared to your front, the car will have a tendancy to oversteer more and handle worse than stock. If anything, bump up the front width and not the rear

 

everybody so far has posted nothing to help you out. I just had my rears replaced with 255/40/18 and yes it does mess with your traction sensors and there is no way around it. So just stick with 245's.

 

This is incorrect. The staggered widths between front and rear actually decrease oversteer. Fitting a 255 in the rear would give you more traction in the rear and you would have increased understeer. (the front end will plow a bit more in turns) Bumping up the front width would promote oversteer since the front end would have more traction.