Hey guys,
I posted this on 997 Turbo section but maybe here is better since it's directly related topic.

I'm buying 20 inch wheels and tires. Tirerack recommends 235/30 front and 305/25 rear. Front tires are almost identical in overall diameter. However I found that 305/25 is slightly smaller and 315/25 will be perfect match to oem 305/30/19.
http://tire-size-conversion.com/tire-size-calculator/
Click on middle tab(Tire size comparison)

Toyo T1R has 315/25/20 available. Should I run 235/315 or 235/305?
Any thoughts?

P.S. Don't tell me "Forget about them and go for 245/325 or even 345". I don't want to run bigger than OEM size.