Tires: upgrading to LT from p-metric, tire placard, ford expedition

Question
QUESTION: I have a 2003 Ford Expedition with P265/70/17 on it now.  We just purchased a 6,000 lb travel trailer that we will be pulling next year.  None of the local tire shops or dealer could advise me on whether I should upgrade to the LT or stay with the P-metric tire for towing.  Towing capacity on this truck is rated at 8,900 +/- lbs.  Any input you can provide would be appreciated.

ANSWER: Andy,

If you are towing within the limitations of the vehicle, then the tire size and pressure as listed on the vehicle tire placard are appropriate.

So your first step is to check your owner's manual or call the vehicle manufacturer and find out what the towing limitations are.  If you within those, then all is well.

I am not a fan of switching from P metric to LT metric tires and vice versa.  The tires are quite different and the vehicles are designed to accommodate that particular type of tire - and not the other.

---------- FOLLOW-UP ----------

QUESTION: I also forgot to ask what is an XL P-metric tire?  What are your thoughts on those tires and would that be a good fit for my Expedition?

Answer
Andy,

An XL (Extra Load) tire is identical to a SL (Standard Load) tire, except that the XL is designed to accommodate higher loads and higher pressures.  An XL can be used in place of an SL, but not the other way.

In the case of towing, there might be an advantage to using an XL, but it might also be unnecessary if you are towing well within the capability of the vehicle.  But certainly, no harm would be done by using an XL in place of a SL.