ResponsE

I currently have the Z06 style rims on my stock C5.
I was wondering about tire fitment as I need to replace my weather cracked Proxes.

The current tires are 245/40ZR18 and 285/40ZR18

I have located a very reasonably priced set of tires that are 255/45ZR18 and 285/40ZR18.

Will this swap work? Will I experience problems? Thanks in advance guys!

Heres a pic of my ride with the aforementioned rims.

rws.1

They will fit and you should be OK

Normally you want about a larger overall diameter on the rear tires so the traction control system does not activate. The on board computer monitors the wheel speed sensors and if it senses the rear wheels are rotating faster that the front , it kicks on the traction control system.....
IF the car is driving at constant speed and the rear tires are smaller diameter than the front, the rear wheel sensors will indicate such a condition since the circumference of a smaller diameter tire means it needs more rotations to match the speed on the larger diameter and circumference front tire.
The current front tires are about 25.7 " diameter ( depends on brand/model)
The proposed front tires are 26.9" diam.
The rears are 27.1"diam
As long as the rears remain larger diameter as they wear compared to the fronts you will not have any issues.

ResponsE

Thanks very much for that detailed and thoughtful response! Cheers RWS!

SMaster

As 8VETTE7 said, those tires are almost the same diameter. I have a set now what are almost the same and I have to turn off traction control everytime I get over 55 MPG or accelerate hard taking off. It's a pain in the butt.

I'd look for a rear tire that is a litte larger in diameter.

mrr23

I had 275/40-17 and 305 / 35-18 on my car with the same wheels.