I am wanting to find the narrowest tire for my truck around 35" maybe 36", in MT or AT, all I can find is 12.50 width's , I would like something around 10.50 for better digging ability and less rolling resistance, Thanks.

 

There aren't a lot of tires taller that don't get wider. 265/70 is the tallest 265 that's commonly made. 275/70 is taller but also wider. The 35's are almost always 12.50" wide. 35x10.50x17 just isn't a size that is commonly made (at least by the brands I deal with).