a 225 will be 20mm wider, 10mm wider per side of the wheel. depending on how it fits on the wheel now will determine, but you could probabl put a 225 on there.
OP:
If you are looking to be nationally competitive or wanna trophy and have every competitive advantage you can, run the 615
if you are just looking to have fun and tires that will be competitive, and work very well, go with the rsII
and as always, more tire = better, so if you can fit a 225 without sidewall rollover issues, id say the 225/45r16 woudl be a winner. but the 215 azenis will stick better than a 225 rsII.
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i like wayfarers.