I test fit 15X8 +20 Kosei K8R borrowed from a NB Miata.

Has 205/50 Federal 595 RS-RR tires (run wider than most tires).

I know there's more questions than answers re:which 15s will fit. I've concluded any 15X8 that has the same inner spacing as a 949 Racing 6UL will fit given the right offset. Most 15X8s and 15X9s marketed towards autocross/track NA/NB Miata's have the same spacing.

These clear brakes with space to spare. The only time it may get hairy is if a tire guy for some reason mounts weight in the middle of the rim.

Anyway, I've got the Kosei K5R same specs in my cart on Tire Rack. Tire choices are a bit limited to have the height necessary for a R56. There's 205/55 that results in just an all season tire and 225/50 that results in Toyo R888 and similar 100 treadware tires. I was looking for 140-200 ideally.

Question is, has anyone run 225/50 on a 15X8? I've seen 225/45 on R53s. Due to the offset I'm not worried about inner clearance, but outer. I anticipate to have another full degree of neg camber by the time these are on.

See attached pics.

 

What are you using these tires for?

see
http://www.tirerack.com/tires/TireSe...earDiameter=17
Not many choices for street tire in 205/55-15

225/45/15 is better for tire selection (Extreme Summer tires)
http://www.tirerack.com/tires/TireSe...earDiameter=17

 

Ideally I wanted them for track days and autocross. I wish the tire selection in 225/50 was near that of 225/45-15.

225/45 is what I run on the Miata's 15X9s.

I ended up getting some cheapo Kumho All seasons to just daily on. They are 225/50. I just feared 225/45 would be too small, especially for a R56. As you can see the 205/50 looked quite small. I'm also not looking to shorten gearing.