Before I go and buy up some tires, I just thought maybe it would be a good idea to ask about the wider tire sizes, or just stick with what I already have.
If it makes any difference now, I have the LS3 engine in there, and they just got the wheel alignment done to tell me his opinion.

rear

225/50r16 – current

245/45r16 – this is .8 inch wider if you’d like to go wider. It should fit under the car fine.



Front

205/55r16 – current

If you want wider you can go up to the 225/50r16 (current rear tire size)

what are the wheel widths? 7s & 8s ?

What size wheels are you running?
I have 7" and 9" and was thinking of 225s and 245s.
With the LS3 (same engine I'm running), I want all the tire I can get.

I believe I have 7's, and 8's.

225/50-16 & 245/45-16 on 7s & 8s are pushing it IMO, but they will fit according to tire size calculators. Depending on the tire brand the sidewalls can look decent or they can look 'sucked in'. But they 'will fit' on the wheels.

I'd bump it up but it really depends on the tire brand. Actual measurements can vary 1"

Stock Boxster is 205/55 on 6" and 225/50 on 7"