1st time at track next Wednesday - need advice

I found two wheels on Craigslist that fit. the offset is a little off, but he let me test fit them and they fit. I am mounting the ET Street Radials tonight and will try a little test drive / launch with them to see how well they work. I usually run 295/50R15 and the ET's are 255/60R15. They are thinner, but actually a little taller. Tomorrow is the big day!