Tires: tire size, tire placard, inflation pressure

Question
My 2002 Dakota Crew Cab 4X4 lists Lt265 70 R 16 tires. The tires I wish to put on the truck Do not come in that size. would Lt245 75 R 16 be okay as they are close in diameter but about 1 inch narrower?

Answer
Jim,

First, your vehicle tire placard should list the tire size as having the "P" in front of it.  That's different than having the letters "LT".  I am not a fan of substituting P's for LT's and vice versa.  Why?  Because you have to use 15 psi more in LT type tires to get the same load carrying capacity as a P type tire.

Having said that, an LT245/75R16 is slightly smaller in load carrying capacity, so you have to use 5 psi more than an LT265/70R16.

So if you look at your vehicle tire placard, I think it will say the original tire size was P265/70R16 with an inflation pressure of 30 psi front / 35 psi rear.  If you are going to use an LT245/75R16, then you should use 50 psi front / 55 psi rear.