Like everyone before me, I hate the RFT's. I don't have to mention all the abysmal behavior that they cause for this nice car. The big difference with me, and most posts is that I didn't buy this car to win the Grand Prix. I want it to be luxurious first , and very sporty second.
Any set of rims that has a 5 bolt holes with a 114.3 MM bolt pattern, and an offset of between 35 to 50 MM will work fine on your SC-430. There is plenty of room in the fender wells. So If you have leaking rims, or don't like the looks of the "Plates, " feel fee to buy just about anything you want with the above spec. 16" through 20" rims are just fine, and will not interfere with your brake calipers. Changing tire size and diameter does not, I repeat, does not adversly effect the handling or tracking of the vehicle.
I choose to get not only a comfortable ride, but tires that last about four times as long as the RFT's. I chose the Michelin Primacy MXM4's. These are super quite, very long life, have extremely great handling, and they looks really stylish on the car. The size I got was the 245x45R17. The reason I chose this size is that they have the same tread width for traction, and the same diameter 25.7", so the speedometer stays accurate. Additionally the 45 side wall ratio gave a nicer smoother ride with superb handling.
See my Member photo. I bought a set 17" X 7.5" X 40mm offset Velox Borzoi rims from Costco for under five hundered dollars, and the tires under eight hundred dollars. The best money I ever spent on the car!
I am just delighted with this choice and strongly recomnd this to anyone who is tired of their SC-430 riding like a truck!