I'm looking at OEM wheels on eBay, but the sizing for the F-Type R is 9J and 10.5J. I've never seen the 'J' designation, and I'm wondering if that's the same as the US F-Type R?

 

J denotes the shape of the wheel that contacts the tire (tyre) bead. <--- see, that is ONE difference between US and UK designations!

I've never seen another letter than J in the modern era.

https://www.tyresizecalculator.com/w...wheel-markings

 

Yes the same.

The 9 or 10.5 is the physical width of the wheel in inches. J is the type of rim bead to ensure compatibility with tyre bead to ensure an air tight seal and the tyre to stay on the wheel during cornering

good explanation of wheel codes here https://www.oponeo.co.uk/blog/how-to...wheel-markings

kev

 

I think those are the widths in inches.

 

Yes. And the different widths are for front & rear wheels.