Tires: Mixing tires on a Durango 4x4, goodyear fortera triple tread, tire placard

Question
RE: 1999 Dodge Durango 4x4. The tire placard reads “P235/75R15/XL”.  This vehicle is used by my wife. It never goes off-road, has no trailer hitch or towing package; never hauls any meaningful loads whatsoever. It is, for all practical purposes, a big, beefy, over-muscled passenger car, and that is all it will ever be used for. In fact, I down-pressured the rear tires from 41psi to 35psi a long time ago to soften the ride. Now I am shopping for new tires. The tire I would most prefer for its superior tread, traction, handling, and ride qualities is only available in an SL, not XL rating. (Goodyear Fortera Triple Tread – This is FYI only, -please remove this sentence if you don’t want any advertising/promotional material in your questions.) Originally, I had only wanted to replace the steering axle tires, but have been told this is an issue on several fronts, especially as the vehicle is a 4x4, not a 4x2. Would this be true? If so, I’d consider replacing all four tires.  Now, the question comes down to: Given the operating environment of this vehicle, is it permissible to use SL rated tires rather than XL rated tires

Answer
Tim,

It is never a good idea to use a tire less capable that what is listed on the vehicle placard.

Having said that, it appears that you have thought this through and realize that you will be losing 150# load carrying capacity PER TIRE.  This puts you a little closer to the edge.

So if you live in a hot climate - CA, AZ, NM, NV, TX, or FL - I would say you should not use the SL - and you should stay with the higher pressure.

But if you live in a cold climate - MI, MN, MA, PA, etc. - then it will be OK - provided you never speed or load the vehicle with more than groceries.

Your other question:  When the 4X4 is engaged, all four tires have to be the same - brand, design, pressure, state of wear - or they will have different rolling diameters - which can cause the drivetrain to bind up, and leads to a transfer case failure.  Very expensive to repair.