Anyone running this size? I'm sticking with 18's with the same offset and some Tein S-tech springs. I'm wondering if I will run into any clerance problems? I'm just looking for a little improvement without degrading the overall ride. I don't track, but I do go on spirited runs. If anyone has pics, with this set up, can you please post them?

I will also be upgrading the sway bars, in the near future. Thanks for the help guys.

 

You won't have any clearance issues at all. In fact in my opinion the tire is to small for a RX8. The correct size would be a 245/40/18 which has an overall diameter of 25.7". The 245/30/18 has an overall diameter of 23.8". You would be loosing 2" of side wall height and most likely would not meet Mazda's minimum load capacity.

 

The 245/40/18 is the most common upsized tire on here.......It fits on the stock rims, and gives a bit extra meat to the tires. There should be no rubbibg problems at all.

245/30/18's are too low profile....and too short.....your speedo would be way out to lunch...plus the ride would be very stiff......Hope it was a typo