My front tires wore down real quick on the front because of bad suspension/steering components (now fixed) and I need to replace them for an 800+ mile trip soon.

The LT245/75r/16 tires on the back are in decent shape and my spare tire is brand new. But the spare is a P245/75r/16 and not LT.
Question is, can I keep the LT's on the back and put the spare P tire on the front along a new P tire that I can buy?

Some people say never to do that, and then some say they've done it just fine... Will it be okay to do it on my truck? Would the difference affect 4WD?

 

Shouldnt be a problem. Its a weight rating thing, so as long as its not exceeded you should be fine. With 4x4 as long as theyre the same size its fine. I have load e and and my spare is load d. The spare has been on the right rear for about a month now.

 

Okay, thanks a bunch. I'm replacing the in a couple days then leaving for the trip in about a week so I'll see how it holds up.

 

I've run my truck like that before with no issues.

 

it'll be fine. LT has a little stronger sidewall and load rating C or D or E.
just air up the P tires to near max, whatever that is.