Tires: Tires and rims, rim width, tire and rim association

Question
I have a lifted truck i have 315/75/16 on now. I want 35/12.5/16 i need to know if they will fit on a 16/8 rim

Answer
Cal,

A 35X12.50R16LT has an allowable rim width range of ....... OK, this gets a bit complicated.  

Officially, a 35x12.50R16LT does not exist.  But there are some folks who are saying that a 35X12.50R16LT is an alternative way of saying LT315/75R16.  Those folks are wrong.

There is a bit more involved that just the physical dimensions as indicated by the "size".  Embedded in the way a tire "size" is stated is a table of nominal dimensions AND a load carrying capacity table (Maximum load vs inflation pressure).

For example, a 31X10.50R15LT has a nominal overall diameter of 30.52" (not 31!), a nominal width of 10.54", and a maximum load carrying capacity of 1765# at 35 psi (Load Range C).

The nearest LT metric tire officially sanctioned by the Tire and Rim Association - the official tire standardizing organization for the US - is LT265/75R15, which has a nominal overall diameter of 30.67", a width of 10.51", and a load carrying capacity of 2405# at 50 psi. (Load Range C)

The Tire and Rim Association does not list a 35X12.50R16LT in its size lineup - and while an LT315/75R16 is very close dimensionally, there are some subtle differences that make this NOT equivalent!.

Nevertheless, an LT315/75R16 has an allowable rim width range of 8 to 10".