IMO, the idea that "non-OEM 225/50-16s are the WRONG SIZE" is misguided, and unnecessarily steers people away from what are probably the best-gripping street tires available, as well as a number of other good alternatives. I've driven on the car on non-oem 225/50-16s and on 245/45-16s. As far as I'm concerned, it ain' no big deal, particularly on the street.

I've never said there's no difference in outright tread width size.
I *have* mentioned that there's very little difference in *section width* between S2k-spec S02's and other tires in the stock 225/50-16 size.

Some random stuff to consider (or not):

Thing 1) Measured tread width has to be somewhat arbitrary. Where on the rounded transition from tread to sidewall do you stop measuring?

Thing 2) Having greater tread width will almost certainly be WORSE in the rain, when loss-of-grip incidents are more likely.

Thing 3) Anecdotal stories of people spinning S2k's on their way to get morning coffee, and blaming it on having the "wrong" tire size, proves nothing other than that people are much more willing to blame "improper" equipment, particularly if there's a ready-made excuse for them, than to admit they were driving like an idiot.

Thing 4) Anecdotal stories of handling differences between worn-down tires and spanking-new tires of a different make and model with full tread squirminess are not very useful either, and prove nothing regarding the OEM S02 vs. other 225/50-16 vs. 245/45-16 tires.

Thing 5) OEM 225/50-16 tires are designed to fit on 6" - 8" rims, just like almost all other 225/50-16s despite their narrower "tread width" measurements. 245/45-16 tires are designed to fit on 7.5" - 9" rims. OEM AP1 rims are 7.5" wide. Which size is a better fit on AP1 rims?

Count the number of Max Performance and Extreme Performance tires available from the Tire Rack in 245/45-16. ZERO. Now count the number of 225/50-16's. A pretty good selection of tires that are worthy of consideration.

Pointing to an arbitrarily-defined "tread width" number and declaring that anything less than that is unacceptable is a little bit simplistic. Handling, particularly real-world STREET handling is NOT simply a function of "tread width".

I see a lot of hand-wringing and anguish over the lack of 245/45-16 tire availability. Again, in my OPINION, this is totally unnecessary. Just get the best tires for your usage, whether it's available in 245/45-16 or only in 225/50-16. Anybody who knows how to drive a high-performance rwd car and doesn't drive like a total ass, should have no problems either way.

If you trust Honda, they specify 225/50-16 tires for the rear.
If you trust the tire rack, they likewise call for 225/50-16s in the rear.
If you trust Jim from the Tire Rack, he has recommended 225/50-16s when 245/45-16s are not available.

By all means don't take my word for anything, I'm just throwing my outlook on the subject out there for consideration.

 

245/45 isnt needed, so as ZDan said, don't stress about getting something in this size. My car came with non-oem 225/50 in the back and unless I'm really trying or have messed up, the back end stays in check. This includes my experience autocrossing on them. I've only spun out once when I was driving way over the limits (50+mph, turning the wheel and jamming on the brakes when the car wasnt already heading in a straight line).

OP, if this is your only set of tires and you do mostly street driving and nothing super aggressive, I'd look for a set of tires with a treadware around 300. If you do get aggressive or autocross, Bridgestone makes a lot of great tires, and the Hankook RS2's mentioned above are great too (though they seem to be sold out everywhere right now). The Bridgestone RE-050's give $100 gift card if you order them right now, or you could also look at the new RE-01R which are very high performance. If you don't drive like an idiot, 225/50 in the rear will be fine, especially with stickier tires.

 

Please answer my question.

Will 215/45/16 RS2's work well with the OEM 16 fronts?

I'm planning on going 215/45/16 front and 245/45/16 rear with the Hankooks.

 

Kind of a big difference between front and rear diameters, 23.6" F, 24.6" R. This would slightly alter the brake bias, biasing the fronts more. That's more stable, but outright braking/stopping distances might increase. You probably wouldn't notice any difference.

Personally I'd prefer to keep the F/R diameters closer, but I don't think you should have any problems.