[msheriff]

I also have and 03, went from 246 to 265s. Did notice slight drop in mpg. No difference in ride or handling. Sits up higher, however, you should ONLY RUN E, 10 ply tires on these trucks!!
If you notice on the side wall, your weight cap. increases when you go to a 265 over a 245.

I keep pressure at 60 front & back until I hook up heavy, then go to 80 rear.

 

[msheriff]

145,000, my bad,,,, thanks for pointing that out. From my experience, 265s on stock rims have been fine. I have towed very heavy and no problem. The 265s are rated for more weight then the 245s. MPG loss I believe was 1-2 mpg. I keep my winter tires in the basement mounted on rims ready to go. I switch them myself about Dec. Just more aggressive tread. The winter tires are 245s but once they are worn I will replace with 265s.

I won't run any larger due to what seems like excessive wear on front bearings once you go larger... just my .02cents worth.