Tires: 4x4 tires, improper inflation, 4x4 tires

Question
I have a 97 F250 4x4 that I bought used that had Cooper LT285/75R16 tires on it. The dealer refuses to replace the tires with the same ones because they are too big for the rims.  Is this true? If so, what is the largest tire I can put on the truck. Also, the front tires became sawtoothed. What causes this. What is the best way to rotate these tires?

Answer
Doug,

Your vehicle came with 7" wheels.  An LT285/75R16 requires a minimum of a 7 1/2" wheel.  The largest tire that will fit on a 7" wheel is an LT265/75R16.

Irregular wear can be caused by many things - misalignment, improper inflation pressure, insufficient rotation, etc.  Certainly the narrow rim contributed to the problem as the tire would be "arched" across the tread face and the shoulders would not be in even contact with the road surface.

The best rotation pattern is called a Modified-X.  The rears tires cross forward and the front tires go straight back.  If you have a full size spare, it is best to include that tire in the pattern as well.  This prevents the spare from becoming too old to use.  

My current recommendation for tire age is 10 years from date of manufacture - 6 years if you live in the following states - CA, AZ, NV, NM, TX, and FL - and proportionally in between for states further north.  For example TN would be 8 years.

Hope this helps.