Can I run two slightly different tire sizes on the front axle vs the rear axle of the truck in the signature, 2004.5 4x4 3500...

I would use 285/70R17 on the front axle and 245/70R19.5 on the rear axle.

A tire calculator shows the difference in diameter to be 1/4 inch between the front and the rear combinations.

The front tires are about 60 % and the rear are brand new so probably the diameters would differ more like 1/2 inch...

If the truck was always in two wheel drive on the pavement would this mismatching any cause powertain or other problems???

Thanks

 

If the truck is a 4x4 don't do it. It could do major damage if it is run in 4 wheel drive even on gravel. It will not hurt if it is never put in 4 wheel drive.