Tire width question...please advise.....

[Sailing2Smth]

I have been running searches on this but came up with half the answer I need....
I know that the BFG Drag Radials 315/30/17 are 12.75 inches in width.

My question is how wide are the 315/30/18?
Any help is appreciated, thanks.

 

[03DOHC]

12.6" on an 11" rim.

http://www.bfgoodrichtires.com/assets/pdf/gforce_ta_drag_radial.pdf

 

[Sailing2Smth]

Thanks for the link Dano!!