I just bought a 2005 Dakota Quad Cab SLT 4.7L 4X4. This Dakota 4X4 has the Full-time AWD. The truck has 2 different brands of tires on the Fronts and Rears, all 4 are the same size 245/70/R16, but I know with other AWD vehicles the 4 tires must be exactly the same tire as to not put pressure on the transfer case. Is it ok to have 2 different brands of tires on this Dakota full-time AWD? I measured the tires, the fronts are 1/2" smaller in diameter than the rears.

 

They all need to be approximately the same size. Depending on how the AWD works, there is some 'built-in' tolerance for variance in tire diameter.... but still, it's best to have all four the same size.