I need new front tires for my sport coupe and am currently running 275/35/19 in the rear. I've been offered a brand new set of PSS in 245/35/19. I know ideally I want a 40 profile but should I just go for it anyways? There'd be a 3.2% difference in rolling diameters. I am rwd so I know it's not as much an issue compared to awd but I've read it can supposedly still effect traction and stability controls. I don't care about the speedometer difference. Any input appreciated.

 

3% seems to be the limit. If your rears have some miles on them, the difference might sneak past the ECU hard limit.