I am looking at 2 different sets of wheels and tires. One has a 34mm offset & 6.3'' backset
and the other has 50mm offset & 6.81'' backset.
They are both 18 x 9 wheels with 255 45 18 tires.
What I need to know what the difference in look will be and if these are the same
diameter as my stock 18'' wheels with 235 50 18 tires.
Also is it possible to buy 4 more TPMS and bands so I can switch sets of tires without the hassle of changing the TPMS twice a year.
I will be having different summer and winter sets of wheels and tires.

 

The 34mm offset will give it a much better stance imo. You can get the TPMS bands here:
http://www.americanmuscle.com/universal-tpms-bands.html

I believe the actual sensors are a dealer item.