215/40-17 on a set of 17x8 with an offset of +43. 02' MCS. Going to be running Raceland coilovers. Trying to get some feedback from anyone that would have experience with a similar set-up.

 

Here, this should help: https://www.wheel-size.com/calc/?whe...cl=50mm&sr=0mm

 

215/40-17 fits wheels 7-8.5" wide, perfect for 7.5" wide rim so you are fine with 17x8" wheel and et+43. The tire will be a bit wide but OK and low profile.

Which tire are you using, mostly performance tires in that size and lower sidewall is stiffer for better handling and responsiveness but firm riding.

 

In my continued research for wheels, I came across a set of 17 x 7 with an offset of +42. I'm considering mounting a set of 205-45-17's on them that I currently have, but I am still thinking about a new set of 215-40-17's in a summer only tire.

 

17x7 et42 is fine and will work with 205/45-17 or 215/45-17 and OEM suspension.

215/40-17 has a stiffer sidewall for better handling but also firm riding. Mostly for track or racing but there are a few others like Ultra HP Summer, Extreme Summer and Grand Touring All Season.

Extreme Summer will give more grip but much faster wear and firmer ride with more noise, good for track and autocross but not good for commuter or daily driving or limited budget.

Ultra High Perf Summer tires give more treadwear and are more street friendly but it is very limited selection for 215/40-17.
Examples from Tirerack.com
Yokohama Advan Fleva V701 treadwear 300 $152.74 each
Tirerack test result for V701
https://www.tirerack.com/tires/tests...y.jsp?ttid=247
Falken FK510 in 215/45-17 is $151 each
Kumho Ecsta PS31 treadwear 460 $126 each
Tirerack test result for PS31
https://www.tirerack.com/tires/tests...y.jsp?ttid=217
Firestone Indy 500 in 205/45-17 is $156 each treadwear 340 XL load rated

As far as tires go the better selection is with 215/45-17