Tires: mounting tires, psi max, tire failure

Question
I was given 4 new 245/70R17 tires to go on my 2500 dodge ram pickup, the truck currently has 265/70R17's, can they be mounted on the same wheels

Answer
Bill,

If your vehicle originally came with LT265/70R17's then you should not mount this tires on your vehicle - they are much lower in load carrying capacity and therefore it is more likely you will have an overloaded tire failure - which sometimes has tragic results.

But just to be sure, find your vehicle placard, which will list the original tire size and the proper pressure for that size.  It is usually located on a doorpost or in the glove box.  

I'll bet it says LT265/70R17 inflated to 50 or 60 psi front / 70 psi rear.

What do the 245/70R17's say on the sidewall?  I'll bet it's 44 psi max.  That ought to tell you they are not interchangeable.

But even if that isn't true and the 245's are LT245/70R17, then the tires have lower capacity (just not as much as they would if the tires are P245/70R17).