Up here is Michigan you are constantly swirving in your lane to avoid potholes. Being chevrolet they reduced the tire diameter from the SC to the TC by 6/10 of an inch,what are the benefits of a smaller tire diameter.?
I thinking it would give a quicker 0-60 timeand better handling.

SS/ SC 215/45-18= 25.61 inches tall.
SS/ TC 225/40-18= 25.08 inches tall.

I know the 225s provide better traction over the 215s but at the sacrifice of less sidewall.

Idealy I wish they used a 235/40/18 which would be 25.4 inches tall. But with the tolerances from car to car, one could have rubbing. The other big issue being tire manufactures do not suggest using 235/40-18 on anything less than 8 inches wide.

 

well you could always use 225/45 on them

 

performance............

smaller sidewall has better turn in characteristics, plus being wider is a plus.

 

Not sure as to GM's reasonings. But I run 45/40/18's and I'm fine. No rubbing, nice meaty sidewall, great traction. And yes, stock ss/sc rims

 

Possibly better tire selection. 215/45R18 is an oddball size previously only widely used on a Ferrari. Stock size selection isn't that great. A lot of people go to 225/40R18 to get a better selection of tire.

You guys are more than likely overthinking things. They probably got a better deal on the TC tires than they did on the SC if they bought the 225/40 size. Money drives most of the automotive industry.

 

i run 225/45s right now