I'm confused with the metric tire sizes. I am going to be running my stock 16" wheels and would like to run a 31x10.5 tire so what metric size is close to that(245/70-245/75 etc.) any help in this area would be greatly appreciated.

I'm confused with the metric tire sizes. I am going to be running my stock 16" wheels and would like to run a 31x10.5 tire so what metric size is close to that(245/70-245/75 etc.) any help in this area would be greatly appreciated.

Closest to 31x10.5 seems to be 265/75R16 or 275/70R16.

I used http://www.miata.net/garage/tirecalc.html.  The 275s are a bit wider, but closer to 31" dia.  But tires don't usually come out at the nominal measurement anyway.